An article reports that when each football helmet in a random sample of 34 suspension-type helmets was subjected to a certain impact test, 24 showed damage. Let p denote the proportion of all helmets of this type that would show damage tested in the prescribed manner.

Required:
a. Calculate a 99% Cl for p.
b. What sample size would be required for the width of a 99% Cl to beat most .10, irrespective of p ?

Answers

Answer 1

Answer:

a

    [tex]0.5043 < p <0.9075[/tex]

b

   [tex]n = 24[/tex]

Step-by-step explanation:

From the question we are told that

    The sample size is  n =  34

    The  number of damaged helmets is  x  =  24

Now the proportion of damaged helmets is mathematically represented as

      [tex]\r p = \frac{k}{n }[/tex]

substituting values

     [tex]\r p = \frac{24}{34 }[/tex]

    [tex]\r p = 0.7059[/tex]

Given that the confidence level is 99% the level of significance can be evaluated as

     [tex]\alpha = 100 - 99[/tex]

     [tex]\alpha = 1[/tex]%

    [tex]\alpha = 0.01[/tex]

Next we obtain the critical value of  [tex]\frac{\alpha }{2}[/tex]  from the normal distribution table, the value is  [tex]Z_{\frac{\alpha }{2} } = 2.58[/tex]

The reason we are obtaining critical values of   [tex]\frac{\alpha }{2}[/tex] instead of   [tex]\alpha[/tex] is because  

[tex]\alpha[/tex] represents the area under the normal curve where the confidence level interval (  [tex]1-\alpha[/tex]) did not cover which include both the left and right tail while  

[tex]\frac{\alpha }{2}[/tex]is just the area of one tail which what we required to calculate the margin of error

   The margin of error is mathematically represented as

     [tex]MOE = Z_{\frac{\alpha }{2} } * \sqrt{\frac{\r p ( 1 - \r p)}{n} }[/tex]

substituting values

      [tex]MOE = 2.58 * \sqrt{\frac{ 0.7059 ( 1 - 0.7059)}{34} }[/tex]

     [tex]MOE =0.2016[/tex]

The 99% confidence interval for p is mathematically represented as

      [tex]p-MOE < p < p + MOE[/tex]

substituting values

       [tex]0.7059 - 0.2016 < p <0.7059 + 0.2016[/tex]

      [tex]0.5043 < p <0.9075[/tex]

The  sample size required for the width of a 99% Cl to beat most 0.10, irrespective of p ? is mathematically represented as  

     [tex]n \ge \frac{ Z_{\frac{\alpha }{2} } * \sqrt{\r p (1- \r p )} }{\frac{\sigma }{2} }[/tex]

Here  [tex]\sigma = 0.10[/tex]  telling  us that the deviation from the sample proportion is  set to 0.10 irrespective of the value of  [tex]\r p[/tex]

so the  sample size for this condition is

    [tex]n \ge \frac{ 2.58 * \sqrt{ 0.7059 (1- 0.7059)} }{\frac{0.10 }{2} }[/tex]

    [tex]n \ge 23.51[/tex]

=>   [tex]n = 24[/tex]


Related Questions

rationalize root six divided by root three minus root two. [tex]\frac{\sqrt{6} }{\sqrt{3}-\sqrt{2} }[/tex]

Answers

Answer:

the answer is

[tex]3 \sqrt{2} + 2 \sqrt{3} [/tex]

Step-by-step explanation:

the explanation is given in the image.

Answer:

[tex]\huge\boxed{\dfrac{\sqrt6}{\sqrt3-\sqrt2}=3\sqrt2+2\sqrt3}[/tex]

Step-by-step explanation:

[tex]\dfrac{\sqrt6}{\sqrt3-\sqrt2}\\\\\text{use}\ (a-b)(a+b)=a^2-b^2\\\\\dfrac{\sqrt6}{\sqrt3-\sqrt2}\cdot\dfrac{\sqrt3+\sqrt2}{\sqrt3+\sqrt2}=\dfrac{\sqrt6(\sqrt3+\sqrt2)}{(\sqrt3-\sqrt2)(\sqrt3+\sqrt2)}=\dfrac{(\sqrt6)(\sqrt3)+(\sqrt6)(\sqrt2)}{(\sqrt3)^2-(\sqrt2)^2}[/tex]

[tex]\text{use}\ \sqrt{a}\cdot\sqrt{b}=\sqrt{ab}\ \text{and}\ (\sqrt{a})^2=a[/tex]

[tex]=\dfrac{\sqrt{(6)(3)}+\sqrt{(6)(2)}}{3-2}=\dfrac{\sqrt{18}+\sqrt{12}}{1}=\sqrt{9\cdot2}+\sqrt{4\cdot3}\\\\=\sqrt9\cdot\sqrt2+\sqrt4\cdot\sqrt3=3\sqrt2+2\sqrt3[/tex]

Rachel Plant has ​$28,000 invested in stock A and stock B. Stock A currently sells for ​$20 a share and stock B sells for ​$80 a share. If stock B doubles in value and stock A goes up​ 50%, her stock will be worth ​$54,000. How many shares of each stock does she ​own?

Answers

Answer:

A= 66.6667

B = 333.3333

Step-by-step explanation:

Initial value of A = $20

Initial value of B = $80

Initial total=$ 28000

A moves up 50%= 20+(0.5*20)

A moves up 50% = 20+10

A moves up 50% =$ 30

B double it values = $80*2

B double it values = $160

Now total value is = $54000

A20+B80= 28000... equation 1

A30+B160= 54000.... equation 2

Multiplying equation 1 * 2

Multiplying equation 2 * 1

A40 +B160 = 56000

A30+B160= 54000

A30 = 2000

A= 2000/30

A= 200/3

A= 66.6667

A20+B80= 28000

Substituting A

200/3 (20) +B80= 28000

B80= 28000-4000/3

B80= 80000/3

B= 80000/240

B = 333.3333

Can u guys tell me the answer to question 8 and 9 thank you so much
I would really appreciate it
Thank you

Answers

Step-by-step explanation:

Q8.  

Step 1.

35.4 - 31 = 4.4

Step 2.

4.4 ÷ 31 = 0.1419....

Step 3.

0.1419.... x 100 = 14.19...

Step 4.

To one decimal place = 14.2% increase

Q9.

Step 1.

£10 ÷ 40 articles = £0.25 = 25p (this is the answer to part a)

Step 2.

32p x 40 articles = £0.32 x 40 articles = £12.80 (this is the answer to part b)

Step 3.

£12.80 - £10 = £2.80 (this is the answer to part c)

Step 4.

£2.80 ÷ £10 = 0.28

Step 5.

0.28 x 100 = 28% (this is the answer to part d)

Hope this was what you were looking for :)

(Also, hi to a fellow Brit - there aren't that many of us around here)

Bluey :)

Question 5 of 13, Step 1 of 1
3/15
Correct
2
The Chandlers are moving across the country. Mr. Chandler leaves 2.5 hours before Mrs. Chandler. If he averages 75 mph and she averages 85 mph, how many hours
will it take Mrs. Chandler to catch up to Mr. Chandler?​

Answers

Answer:

It will take Mrs Chandler 18 hours 45 minutes or 18.75 hours to catch up Mr Chandler

Step-by-step explanation:

What we want to know here is that at how many hours will they have traveled same distance.

Let the total time taken by Mrs Chandler to catch up be x hours

Since Mr Chandler left 2.5 hours earlier , then the total time taken by him would be x + 2.5 hours

Now, we know that distance = speed * time

Since it’s same distance covered;

For Mr Chandler, his distance is calculated as 75(x + 2.5)

For Mrs Chandler, her distance is calculated as 85x

We equate both since they are equal;

75(x + 2.5) = 85x

75x + 187.5 = 85x

85x -75x = 187.5

10x = 187.5

x = 18.75 hours or 18 hours 45 minutes

simple khan academy math help asap

Answers

Answer:

[tex]\boxed{\sf C. \ 6.6 \ units}[/tex]

Step-by-step explanation:

The triangle is a right triangle.

We can use trigonometric functions to solve.

[tex]\sf cos(\theta)=\frac{adjacent}{hypotenuse}[/tex]

[tex]\sf cos(35)=\frac{MO}{8}[/tex]

[tex]\sf 8 \ cos(35)=MO[/tex]

[tex]\sf 6.55321635...=MO[/tex]

You are returning from Mexico and want to convert 5,00 pesos to US dollar . The rate of exchange that day is 1 pesos is 0.55 . How many dollars will you receive for your pesos ?

Answers

Hey there! I'm happy to help!

We see that 1 peso is equal to 0.55 U.S. dollars. So, the amount we will get in U.S dollars is the same as $5000×0.55 because 0.55 US dollars is equal to one peso!

5000×0.55=2750

Therefore, you will receive $2750.

Have a wonderful day!

Please answer this correctly without making mistakes

Answers

Answer:

I believe 45.50

Step-by-step explanation: The locksmith is 18.3 miles W from furniture, the hotel is 27.2 E from furniture store  so 18.3+27.2=45.50

The answer 45.5 kilometers


Step by step is below

Hopefully this help you you

Have a great day :)

Can you help me solve this question? (Also explain me how is it possible)

Answers

Answer:

Answer B) (2 times )

Step-by-step explanation:

Let's start with the person that shook hands more (Dora), so we already know how four of this connections took place See attached image.

step 1:

D is connected to A, B, C, and E

Step 2:

Now proceed with the connections for the second greatest (C who shook hands with 3 people). Notice that C is already connected with D, and can connect with B and with E, but NOT with A (since this person shook hands only once - with D. So C is connected to B, D, and E completing the three handshakes.

step 3: Now just corroborate that B is already connected to two people (C and D).  So just count the number of connections that E is left with: 2 handshakes.

Answer:

( E ) 0

Step-by-step explanation:

Solution:-

- There can be two ways in solving this question. Either we lay-out a map of every person ( Alan, Bella, Claire, Dora, and Erik ) shaking hands with each other.

- We will use an intuitive way of tackling this problem.

- We have a total of 5 people who greeted each other at the party.

- Each of the 5 people shook hands exactly " once "! We can give this a technical term of " shaking hands - without replacement ".

- We will define our event as shaking hands. It takes 2 people to shake hands.

- We will try to determine the total number of unique "combinations" that would result in each person shaking hands exactly one time.

- We have a total of 5 people and we will make unique combinations of 2 people shaking hands. This can be written as:

                            5C2 = 10 possible ways.

- So there are a total of 10 possible ways for 5 people to greet each other exactly once at the party.

- We are already given the data for how many handshakes were made by each person as follows:

                      Name                 Number of handshakes

                       Alan                                   1

                       Bella                                  2

                       Claire                                 3

                       Dora                                   4

               =======================================

                      Total                                  10

               =======================================

- So from the data given. 10 unique hand-shakes were already done by the time it was " Eriks " turn to go and greet someone. This also means that Erik has already met all 4 people in that party. So he doesn't have to approach anyone to shake hands and know someone. He is already been introduced to rest of 4 people in the group.

Answer: Erik does not need to shake hands with anyone! He is known and greeted rest of the 4 people on the group.

At noon, ship A is 70 km west of ship B. Ship A is sailing south at 35 km/h and ship B is sailing north at 25 km/h. How fast is the distance between the ships changing at 4:00 PM

Answers

Answer:

57.6 km/h

Step-by-step explanation:

We are told that At noon, ship A is 70 km west of ship B.

Thus, coordinates of initial position of A and B is;

A(0,0) and B(70,0)

Now, we are told that Ship A is sailing south at 35 km/h and ship B is sailing north at 25 km/h. Thus, the final position of ship A and B after t hours are;

A(0,-35t) and B(70,25t)

Thus, distance between the two ships at time t hours is;

d(t) = √[(70 - 0)² + (25t - (-35t))²]

d(t) = √(4900 + 3600t²)

Now, to find how fast the distance between the ships changing, let's differentiate using the chain rule;

d'(t) = [1/(2√(4900 + 3600t²))] × 7200t

d'(t) = 3600t/√(4900 + 3600t²)

d'(t) = 3600t/10√(49 + 36t²)

d'(t) = 360t/√(49 + 36t²)

Now, at 4pm,it would have been 4 hours from noon. Thus, t = 4.

So;

d'(t) = (360×4)/√(49 + 36(4²))

d'(t) = 1440/√(49 + 576)

d'(t) = 1440/√625

d'(t) = 1440/25

d'(t) = 57.6 km/h

16. Use yesterday’s stock table for the company Icarus to answer the following questions.

52-week Price
High Low
Stock
Symbol
Dividend
Annual Yield Return (%)
P/E ratio
Volume Traded
High Low
Price Price
Closing Price
Net Change
28.38 15
Icarus
ICR
0.41
1.1
24
105300
24 23.5
24
. . . .

a. What was the high price for Icarus stock over the last 52 weeks?​​​​16a. _______________

b. If you owned 1000 shares of Icarus stock last year, what is the dollar amount of the ​​b. _________________
dividend you received?
c. What is the annual yield return for dividends alone?​​​​​​c. _________________

d. How many shares of Icarus stock were traded yesterday?​​​​​d. _________________

e. What was the low price for Icarus stock yesterday?​​​​​​e. _________________

f. What was the price of Icarus stock at the close of the stock exchange yesterday?​​f. _________________

g. Compute Icarus’s annual earnings per share using the formula below.​​​​g. _________________

Answers

D I believe this is correct

Find the balance in Asturos savings account if he deposits $2100 at 3.5% simple interest for 2 years

Answers

Answer:

2250

Step-by-step explanation:

Balance : 2100

2 Years

2100 ÷ 100 x 103.5 ÷ 100 x 103.5 = 2249.5725

DIRECTIONS: Road the question and select the best respons
A right prism of height 15 cm has bases that are right triangles with legs 5 cm and 12 cm. Find the total
surface area of the prism,
OA 315 cm square
OB, 480 cm square
Oc. 510 cm square
OD. 570 cm square

Please explain how to get the answer

Answers

Answer:

C. 510 cm^2

Step-by-step explanation:

Well to find TSA or Total Surface Area,

We need to find the area of al the triangles and rectangles.

Let's start with the 2 rectangles facing forwards.

They both have dimensions of 5*15 and 12*15,

75 + 180

= 255 cm ^2

Now let's do the back rectangle which has dimensions of 15 and 13.

15*13 = 195 cm^2

Now we can do the top and bottom triangles,

Since we don't have height we can use the following formula,

[tex]A = \sqrt{S(S-a)(S-b)(S-c)}[/tex]

S is [tex]S = \frac{1}{2} (A+B+C)[/tex]

S= 15

Now with s we can plug that in,

[tex]A = \sqrt{15(15-5)(15-13)(15-12)}[/tex]

The a b and c are the sides of the triangle.

So let's solve,

15 - 5 = 10

15 - 13 = 2

15 - 12 = 3

10*2*3 = 60

60*15 = 900

[tex]\sqrt{900}[/tex] = 30 cm^2

Since there is 2 triangles with the same dimensions their areas combined is 60 cm^2

60 + 255 + 195 = 510 cm^2

Thus,

the TSA of the right triangular prism is C. 510 cm^2.

Hope this helps :)

Answer:

C) 510 square centimetres

Step-by-step explanation:

The surface area of a prism is given as:

A = bh * pL

where b = base length of the prism = 12 cm

h = base width = 5 cm

p = b + h + c

where c = slant height = 13 cm

L = height of the prism = 15 cm

Therefore, the surface area of the prism is:

A = (12 * 5) + (12 + 5 + 13) * 15

A = 60 + (30 * 15)

A = 60 + 450

A = 510 square centimetres

That is the surface area of the prism.

What is the quotient matches 22/33 divided by 6/9

Answers

Hey there! I'm happy to help!

When you divide fractions, you are technically multiplying by the reciprocal, which is the numerator and denominator flipped. This means that 22/33 divided by 6/9 is equal to 22/33 multiplied by 9/6.

If we multiply these together, we get an answer of 1.

I hope that this helps! Have a wonderful day!

The calculated division of the numbers 22/33 divided by 6/9 is 1

How to calculate the division of the numbers

From the question, we have the following parameters that can be used in our computation:

22/33 divided by 6/9

When represented as an equation, we have

22/33 divided by 6/9 = 22/33 ÷ 6/9

Represent as a product expression

So, we have

22/33 divided by 6/9 = 22/33 * 9/6

So, we have the following result

22/33 divided by 6/9 = 1

Using the above as a guide, we have the following:

the result is 1

Read more about quotient at

brainly.com/question/11418015

#SPJ6

box with a a square base and open top must have a volume of 62,500 cm3. Find the dimensions of the box that minimize the amount of material used. sides of base

Answers

Answer:

The dimensions of the box that minimize the amount of material used is 39.69 cm

Step-by-step explanation:

This problem is on the mensuration of solids, a box

we know that the volume of a box is give by the expression

[tex]Volume= L^3[/tex]

now to find the dimension of the box, we need to find L

Given data

volume = [tex]62,500 cm^3[/tex].

[tex]62,500 cm^3= L^3\\L=\sqrt[3]{62500} \\\L=39.69 cm[/tex]

Answer:

The dimensions of box that will minimize the amount of material used is [tex]39.69cm[/tex]

Step-by-step explanation:

Given information

Volume [tex]V=62500cm^3[/tex]

As given in question the box is of square shape:

So the volume will be

[tex]V=L^3[/tex]

where, L is the side of the square

[tex]V=L^3=62500\\L=\sqrt[3]{62500} \\L=39.69 cm\\[/tex]

Hence, The dimensions of box that will minimize the amount of material used is [tex]39.69cm[/tex].

For more information visit

https://brainly.com/question/23245822?referrer=searchResults

Facespace is a popular form of social media. Recent reports show that the mean time spent on Facespace is 35 minutes a day with a standard deviation of 6 minutes a day. The data is normally distributed. If 1100 people are on in one sitting, how many of them lie within one standard deviation below the mean and two standard deviations above the mean?

Answers

Answer:

897

Step-by-step explanation:

I think it deleted my prior solution because I linked the Wikipedia article for the empirical rule... So to retype this:

We'll be using the empirical, or 68-95-97.5 rule of normal distributions which says that 68% of data in a normal distribution is within 1 standard deviation, 95% is within two, and 97.5% is within three. Graphical representations of the rule can be found online and may be helpful to understand it more easily.

The first part of the problem is relatively straightforward, to get the two pieces within one standard deviation, that's 68% of the total population of 1100. So, 0.68*1100=748.

The second part is a bit trickier, since it is just the part of the second standard deviation out that is above the mean. To get this, we need to think about the difference between one standard deviation out and two, percentage-wise. Since two standard deviations out is 95% of the data, the difference between one and two is 95%-68%, or 27% of the data. However, since we only want the upper half of that, we'll just be using 13.5%. So our second piece is 13.5% of 1100, or 148.5.

Add together our two pieces, 748+148.5=896.5 and round up to 897.

Really need help on question 10.

Answers

Answer:

44 degrees

Step-by-step explanation:

4 multiplied by 7 is 28.

28 + 2 = 30

angle ABC = 30 degrees

3 multiplied by 7 is 21

21 - 7 = 14.

angle CBD = 14 degrees.

30 + 14 = 44.

The answer is ABD = 44 degrees

WILL MAKE BRAINLIST----- Describe both rotational symmetry and reflection symmetry. Find four examples of symmetry in your classroom.

Answers

Answer:

When an obect has rotational symmetry, that means the object will look the same after a certain amount of rotating. When an object has reflection symmetry, it means the object mirrors itself at the midpoint.

Step-by-step explanation:

Find the reciprocal of 5/6, b≠0

Answers

Answer:

6/5

Step-by-step explanation:

The reciprocal of 5/6 means flip it

6/5

Answer:

6/5

Step-by-step explanation:

The reciprocal of a fraction is switching the numerator with denominator.

5/6 ⇒ 6/5

A congressman wants to measure the level of support in his district for campaign finance reform and determine if there is a gender gap among voters with respect to this issue. One aid suggests that they find separate confidence intervals for the percent of men and the percent of women who favor reform and then see if the intervals overlap. Another aid suggests that they find a confidence interval for the difference in the proportions of men and women who favor reform. The question is: Is there a gender gap

Answers

Answer:

Campaign Finance Reform

Gender Gap among Voters in the District

There is a gender gap among women and men who favor campaign finance reform.

Step-by-step explanation:

In issues such as the above, a gender gap always exist between women and men who think that there is the need to reform the campaign finance.  Women ordinarily favor a reduction in the campaign finance.  On the other hand, men do not mind so much about the candidate expenditure in campaigns.  Reducing the huge campaign finance will ensure that political campaigns and aspiration to political offices are not left to money bags.  Many women would like to get involved, but they are limited by funding.  So, anytime the issue of reforming the whole electoral system, especially with respect to campaigns, women favor the reforms more than men.  The gap is always there.  The main issue is how would this gap be measured?

a beetle sets out on a journey. on the first day it crawls 1m in a straight line. on the second day it makes a right-angled turn (in either direction) and crawls 2m in a straight line. on the third day it makes a right-angled turn (in either direction) and crawls 3m in a straight line. this continues each day with the beetle making a right-angled turn ( in either direction and crawling 1m further than it did the day before. what is the least number of days before the beetle could find itself stopped at its starting point?

Answers

Answer:

  7

Step-by-step explanation:

The signed sum of sequential odd numbers must be zero, as must the signed sum of sequential even numbers.

The minimum number of sequential even numbers that have a sum of 0 is 3: 2+4-6 = 0.

The minimum number of sequential odd numbers with a sum of zero is 4: 1-3-5+7=0.

Since we start with an odd number, we can get these sets of numbers in 7 days. The attached diagram shows one possible route.

Farmers Jay, Peter, and Sam own rectangular farms, as indicated in the figure. Jay owns 2 acres of land, Peter owns 4 acres and Sam owns 6 acres. Find the area of the common pasture. PLEASE HELP ASAP!

Answers

Answer:

Area of the common pasture = 12 acres

Step-by-step explanation:

Let the dimensions of the farm owned by Jay are 'a' units and 'b' units.

Area of the farm = ab = 2 acres

Similarly, areas of the farm owned by Peter with dimensions 'a' unit and 'c' unit = ac = 4 acres

And area of the farm owned by Sam with dimensions 'b' and 'd' units = bd = 6 acres

Now, [tex]\frac{ab}{ac}=\frac{2}{4}[/tex]

[tex]\frac{b}{c}=\frac{1}{2}[/tex] ---------(1)

[tex]\frac{ab}{bd}=\frac{2}{6}[/tex]

[tex]\frac{a}{d}=\frac{1}{3}[/tex] ---------(2)

[tex]\frac{b}{c}\times \frac{a}{d}=\frac{1}{2}\times \frac{1}{3}[/tex]

[tex]\frac{ab}{cd}=\frac{1}{6}[/tex]

cd = 6(ab)

cd = 6 × 2 [Since ab = 2 acres]

    = 12 acres

Therefore, area of the common pasture will be 12 acres.

Which Graph represents the solution to the compound inequality 4x +8< -16 or 4x + 8 > 4

Answers

Answer:

Step-by-step explanation:

We can solve each inequality apart and then see the possible solution sets.

Consider the inequality 4x+8 < -16. If we divide by 4 on both sides, we get

x+2 < -4. If we substract 2 on both sides we get x<-6. So the solution set for this inequality is the set of real numbers that are less than -6 (lie to the left of the point -6).

Consider 4x+8>4. If we divide by 4 on both sides we get x+2>1. If we substract 2 on both sides we get x>-1. So the solution set for this inequality is the set of real numbers that are bigger than -1 (lie to the right of the point -1).

So, for us to have 4x+8<-16 or 4x+8>4 we must have that either x <-6 or x>-1. So the solution set for the set of inequalities is the union of both sets, that is

[tex](\-infty, -6) \cup (-1,\infty)[/tex]

Using the unit circle, determine the value of cos(945°).

Answers

Answer: Choice B.  [tex]-\frac{\sqrt{2}}{2}[/tex]

========================================================

Explanation:

The angle 945 degrees is not between 0 and 360. We need to adjust it so that we find a coterminal angle in this range. To do this, subtract off 360 repeatedly until we get into the right range

945 - 360 = 585, not in range, so subtract again

585 - 350 = 225, we're in range now

Since 945 and 225 are coterminal angles, this means cos(945) = cos(225)

From here, we use the unit circle. Your unit circle should show the angle 225 in quadrant 3, which is the lower left quadrant. The terminal point here at this angle is [tex]\left(-\frac{\sqrt{2}}{2}, -\frac{\sqrt{2}}{2}\right)[/tex]

The x coordinate of this terminal point is the value of cos(theta). Therefore  [tex]\cos(225^{\circ}) = -\frac{\sqrt{2}}{2}[/tex] and this is also the value of cos(945) as well

Using the periodic property of cos function, you can evaluate the value of cos(945°).

The value of cos(945°) is given by:

[tex]cos(945^\circ) = -\dfrac{1}{\sqrt{2}}[/tex]

Given that:To find the value of cos(945°) using the unit circle.

What are periodic functions?


A function returning to same value at regular intervals of specific length(called period of that function).

What is the period of cosine function?

It is [tex]2\pi[/tex]

Thus, we have:

[tex]cos(x) = cos(2\pi +x) \: \forall \: x \in \mathbb R[/tex]

Using the periodic property of cosine:

[tex]cos(945^\circ) = cos(2 \times 360^\circ + 225^\circ) = cos(2\pi + 2\pi + 225)\\ cos(945^\circ) = cos(2\pi) + 225) = cos(225^\circ)[/tex]

There is a trigonometric identity that:

[tex]cos(\pi + \theta) = -cos(\theta)[/tex]

Thus:

[tex]cos(945^\circ) = cos(225^\circ) = cos(180^\circ + 45^\circ) = -cos(45^\circ) = -\dfrac{1}{\sqrt{2}}\\ cos(945^\circ) = -\dfrac{1}{\sqrt{2}}[/tex]

Note that wherever i have used [tex]\pi[/tex], it refers to [tex]\pi ^ \circ[/tex] (in degrees).

Thus, the value of cos(945°) is given by:

[tex]cos(945^\circ) = -\dfrac{1}{\sqrt{2}}[/tex]

Learn more about periodicity of trigonometric functions here:

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Phuong collects Persian and Oriental rugs in a ratio of 3:4. If Phuong has 84 Oriental rugs, how many rugs are in his collection?

Answers

Answer:

The answer is

147

Step-by-step explanation:

Let the total number of rugs be x

To find the total number of rugs we must first find the total parts which is

3 + 4 = 7

4/7 of the total rugs are 84 Oriental rugs

Which is written as

[tex] \frac{4}{7} x = 84[/tex]

Multiply through by 7

[tex]7 \times \frac{4}{7} x = 84 \times 7[/tex]

Simplify

[tex]4x = 588[/tex]

Divide both sides by 4

[tex] \frac{4x}{4} = \frac{588}{4} \\ \\ \\ \\ x = 147[/tex]

The total number of rugs is 147

Hope this helps you

The summer has ended and it’s time to drain the swimming pool. 20 minutes after pulling the plug, there is still 45 000L of water in the pool. The pool is empty after 70 minutes.

Calculate the rate that the water is draining out of the pool.


b) Calculate how much water was in the pool initially.
c) Write an equation for this relationship.
d) Use your equation to calculate how much water is in the pool at
62 minutes.

Answers

Answer:

  a) -900 L/min

  b) 63000 L

  c) v = -900t +63000

  d) 7200 L

Step-by-step explanation:

a) You are given two points on the curve of volume vs. time:

  (t, v) = (20, 45000) and (70, 0)

The rate of change is ...

  Δv/Δt = (0 -45000)/(70 -20) = -45000/50 = -900 . . . . liters per minute

__

b) In the first 20 minutes, the change in volume was ...

  (20 min)(-900 L/min) = -18000 L

So, the initial volume was ...

  initial volume -18000 = 45000

  initial volume = 63,000 . . . . liters

__

c) Since we have the slope and the intercept, we can write the equation in slope-intercept form:

  v = -900t +63000

__

d) Put the number in the equation and do the arithmetic.

When t=62, the amount remaining is ...

  v = -900(62) +63000 = -55800 +63000 = 7200

7200 L remain after 62 minutes.

What is the scale factor of ABC to DEF?

Answers

Answer:

B.3

Step-by-step explanation:

to get the scale factor divide a side from the bigger triangle by the equivalent in the small one

15/5 = 3

A wire that is 76 feet long needs to be divided into lengths using the ratio 1 to 13. What is the longer length? Round your answer to two decimal places if necessary.

Answers

Answer:

70.59 feet

Step-by-step explanation:

There are a total of 14 parts when the wire is divided into a ratio of 1 to 13.

1. Divide 76 by 14

76 ÷ 14 = 5.43

2. Multiply the longer length of 13 parts

5.43 · 13 = 70.59

The longer length of the wire 70.59 feet

There are a total of 14 parts when the wire is divided into a ratio of 1 to 13.

1. Divide 76 by 14

76 ÷ 14 = 5.43

2. Multiply the longer length of 13 parts

5.43 · 13 = 70.59

What is a decimal in numbers?

In algebra, a decimal number can be defined as a range whose entire number part and the fractional element are separated by means of a decimal point. The dot in a decimal range is referred to as a decimal point. The digits following the decimal factor show a price smaller than one.

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There are 45 balloons: 15 are blue; 20 are green; 10 are red. 3 balloons are selected for the float. Leaving your answers in combinatorics format, how many ways can all 3 be selected such that they are the same color.

Answers

Answer: Required number of ways =  1715

Step-by-step explanation:

Given, there are 45 balloons: 15 are blue; 20 are green; 10 are red.

3 balloons are selected for the float.

Number of combinations to select r things out of n things : [tex]^nC_r=\dfrac{n!}{r!(n-r)!}[/tex]

So, the number of ways to select 3 ballons such that they are the same color = (Ways to select all blue ) x (Ways to select all green ) x (Ways to select all red)

[tex]^{15}C_3+^{20}C_3+^{10}C_3\\\\=\dfrac{15!}{12!\times3!}+\dfrac{20!}{17!\times3!}+\dfrac{10!}{7!\times3!}\\\\=\dfrac{15\times14\times13}{6}+\dfrac{20\times19\times18}{6}+\dfrac{10\times9\times8}{6}\\\\=455+1140+120\\\\=1715[/tex]

Hence, Required number of ways =  1715

Find (g/f)(x) for the given functions: f(x) = 5/x and g(x) = 3 + x/5

Answers

Step-by-step explanation:

just substitute the value of g(X) and f(X)

Given a rectangle with an area of 20 square units, if the width is x units and the length is x + 1 units, what is the difference between the length and the width?

Answers

Answer: 1unit.

Step-by-step explanation:

Area of the rectangle

A = length × width

Since the area = 20 and the width is x and the length is x + 1.

We now substitute for the values in the above formula and solve for x

20 = x × x + 1

20 = x( x + 1 ), we now open

20 = x² + x , then re arrange.

x² + x - 20 = 0, this is a quadratic equation.we solve for x using quadratic means

Here, I am going to solve using factorization by grouping

x² + x - 20 = 0

x² + 5x - 4x - 20 = 0

x( x + 5 ) - 4( x + 5 ) = 0

( x + 5 )( x - 4 ). = 0

Therefore, the solution for x will be

x = -5 or 4, but x can not be -5 ( negative), so x = 4.

Now the difference between width and the length can easily be calculated from the above,

Width = 4 (x) , and length = 5 (4 + 1),

Now difference will be

5 - 4 = 1unit.

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