The telephone numbers in a small town have two digits. They run from 00 to 99.

Of the 100 possible numbers, those that become smaller when reversed are not used, i.e. 21 is not used.

What is the maximum number of telephone numbers this town could have?

Answers

Answer 1

Answer:

[tex]55[/tex]

Step-by-step explanation:

We'll be using case-work to solve this problem. Let's call the ones digit of the telephone number [tex]B[/tex] and the tens digit [tex]A[/tex]. Each telephone number can be represented as [tex]AB[/tex].

Since the question states that numbers that are smaller when their digits are reversed are not used, we have the following inequality:

[tex]B\geq A[/tex]

This is because if [tex]A>B[/tex], the number would become smaller when [tex]A[/tex] and [tex]B[/tex] are switched in [tex]AB[/tex]. However, if [tex]A=B[/tex] or [tex]B>A[/tex], the number will not become smaller.

Let's work our way up starting with [tex]A=0[/tex]. If [tex]A=0[/tex], there are 10 other numbers (0-9) that we can choose for [tex]B[/tex] that adhere to the condition [tex]B\geq A[/tex]:

[tex]0B,\\01, 02, 03,...[/tex]

Therefore, there are 10 possible telephone numbers when the tens digit is 0.

Repeat the process, now assigning [tex]A=1[/tex]. Now, we only have the digits 1-9 to choose from for [tex]B[/tex], since [tex]B[/tex] needs to be greater than or equal to A. Therefore, there are 9 possible telephone numbers when the tens digit is 1.

This pattern continues. As we work our way up through the cases (when increasing [tex]A[/tex] by 1), the number of possible telephone numbers decreases by 1, since there becomes one less option for [tex]B[/tex].

The last case would be [tex]A=9[/tex] in which case there would only be one option for [tex]B[/tex] and that would be 9.

Since there are 10 cases (0-9), add up the possible telephone numbers for each case:

[tex]\displaystyle \sum_{n=1}^{10}n=1+2+3+4+5+6+7+8+9+10=\boxed{55}[/tex]

Alternatively, recall that the sum of this series can be found using [tex]\frac{n(n+1)}{2}[/tex], where [tex]n[/tex] is the number of values in the set. In this case, [tex]n=10[/tex], and we have:

[tex]1+2+3+4+5+6+7+8+9+10=\frac{10(11)}{2}=\frac{110}{2}=\boxed{55}[/tex]


Related Questions

7 less than the quotient of a number 5 and w in a algebraic expression.

Answers

Answer:

5/w -7

Step-by-step explanation:

quotient means division

5/w

less than means it comes after

5/w -7

Answer:

5/w-7

Step-by-step explanation:

First, let's write out "the quotient of a number 5 and w"

The quotient is the result from dividing two numbers. Therefore, we must divide 5 and w.

5/w

Now, let's add on "7 less than". Since it is "less than" it will come after the division. "Less" means subtract. So, subtract 7 from 5/w.

5/w-7

7 less than the quotient of a number 5 and w as an expression is: 5/w-7

n/8 = (-7) help please

Answers

Answer:

n = -56

Step-by-step explanation:

n/8 = (-7)

Multiply each side by 8

n/8* 8 = (-7)*8

n = -56

Answer:

[tex]n=-56[/tex]

Step-by-step explanation:

We can use algebra and simplify the equation until we have n isolated.

[tex]\frac{n}{8} = -7\\\frac{n}{8}\cdot8 = -7\cdot8\\\\n=-56[/tex]

Hope this helped!

Chen is baking muffins and banana bread for a brunch buffet. He needs 3 and one-fifth cups of flour to make the muffins and 3 and two-thirds cups of flour to make the banana bread. Which is the best estimate of the number of cups of flour that Chen needs to bake both recipes?

Answers

Options :

A. 6 cups of flour

B.7 cups of flour

C.8 cups of flour

D.9 cups of flour

Answer:

B.7 cups of flour

Step-by-step explanation:

Given the following :

Cups of flour required to make muffins = 3 1/5

Cups of flour required to make banana = 3 2/3

Number of cups of flour required to make both recipe :

(cups of flour required to make muffins + cups of flour required to make bread)

(3 1/5 + 3 2/3) = 3+3+(1/5 + 2/3)

= 6 + (1/5 + 2/3) = (3 + 10)/15 = 6 + (13/15)

6 13/15 = 6.8666666

The best estimate is to round to the nearest whole number = 7

Answer: The answer is 7

Step-by-step explanation:

I got it right in my quiz! Hope this helps (:

the Marked price of a book is rupees 200 if a discount of 10% is offered find the selling price of the book​

Answers

Answer:

Rs 180

Step-by-step explanation:

sp=200

discount=10%

10/100*200=20

200-20

180

Angle Terminology with Equations
Aug 03, 8:18:32 AM
?
ZA and ZB are complementary angles. If m2A = (2x – 10)° and m
B = (x - 2), then find the measure of ZA.
EN O
Answer:
Submit Answer
attempt 1 out of 2
Pls help

Answers

If both are complementary then their sum will be 90°

[tex]\\ \sf\longmapsto m<A+m<B=90[/tex]

[tex]\\ \sf\longmapsto 2x-10+x-2=90[/tex]

[tex]\\ \sf\longmapsto 2x+x-10-2=90[/tex]

[tex]\\ \sf\longmapsto 3x-12=90[/tex]

[tex]\\ \sf\longmapsto 3x=90+12[/tex]

[tex]\\ \sf\longmapsto 3x=102[/tex]

[tex]\\ \sf\longmapsto x=\dfrac{102}{3}[/tex]

[tex]\\ \sf\longmapsto x=34[/tex]

Now

[tex]\\ \sf\longmapsto <A=2x-10=2(34)-10=68-10=58[/tex]

Suppose you want to represent the desert temperature in degrees Fahrenheit instead. How would you transform the function C(t) to make the new function, F(t)?

Answers

Answer:

(1c times 9/5) +32

That is the way  to figure out °1c as 33.8°

Hope it helped

PLEASE HELP ME ANSWER THIS QUESTION ​

Answers

Answer:

x = 0

y = -2

Step-by-step explanation:

2304.06 is written in expanded form

4 is unit place. So, 4 *10⁰ = 4 * 1 = 1    {Any integer to the power of 0 is 1}

x = 0

6 is hundredth place = 6 * 1/100 = 6*10⁻²

y= -2

whats the squareroot of 18

Answers

Answer:

it should be 4.24264068712 looked it up

Answer:

18 doesn't have a square root but you can simplify it

[tex] \sqrt{18 } [/tex]

then you take 9 which is a square number and divide it to get 3 which you'll place on the outside

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

I need an explanation written out for (0.345)(2.1)
Thank you

Answers

1449/2000 , 7.245 x 10^-1 = 0.7245

Answer:

0.07245

Step-by-step explanation:

Just work out 345*21 and then divide by 10,000 because 0.345 is 3 digits from zero and 2.1 has 1 digit from zero, so total of 4 zeroes (10,000 since 10,000 has 4 zeroes).



Find the distance between the points J( – 8,0) and K(1, 4).
The exact distance between the two points is

Answers

Answer:

The answer is

[tex] \sqrt{97} \: \: units[/tex]

Step-by-step explanation:

The distance between two points can be found by using the formula

[tex]d = \sqrt{ ({x1 - x2})^{2} + ({y1 - y2})^{2} } [/tex]

where

(x1 , y1) and (x2 , y2) are the points

From the question the points are

J( – 8,0) and K(1, 4)

The distance between them is

[tex] |JK| = \sqrt{ ({ - 8 - 1})^{2} + ({0 - 4})^{2} } \\ = \sqrt{ ({ - 9})^{2} + ( { - 4})^{2} } \\ = \sqrt{81 + 16} \\ [/tex]

We have the final answer as

[tex] \sqrt{97} \: \: \: units[/tex]

Hope this helps you

Tell whether the line for x = -5 is horizontal, vertical, or neither.

Answers

Answer:

vertical

Step-by-step explanation:

The line x = -5 includes all points where the value of x is -5, regardless of the value of y. This can be graphed as a vertical line going through (-5, 0), as the line represents the only place where x is the value -5.

The perimeter of a rectangle is 10 feet. If twice the width is equal to half of the length , find the dimensions of this rectangle.

WRITE AS AN EQUATION​

Answers

Answer:

w = 1ft

l = 4ft

Step-by-step explanation:

P  =2w + 2l

2w = l/2 => l = 4w

10ft = 2w + 2×4w

10ft = 2w + 8w

10ft = 10w

w = 10ft/10

w = 1 ft

l = 4w

l = 4×1ft

l = 4 ft

Answer:

length = 4 ft

Width = 1 ft

Step-by-step explanation:

Let length = l ft

Width = w feet

[tex]\frac{1}{2}l = 2w\\\\l = 2w*2\\\\l = 4w[/tex]

Perimeter = 10 ft

2*(l +w)= 10

2*( 4w + w ) = 10

2*5w = 10

10w = 10

Equation:  10w = 10

Divide both sides by 10

10w/10 = 10/10

w = 1 ft

Plug in the value of w in l = 4w

l = 4 *1

l = 4 ft

A local gym charges a $25 monthly membership fee plus $2 per hour for aerobics classes. What is the linear equation that describes the relationship between the total monthly cost (Y) and the number of class hours each month (X)

Answers

Answer:

The equation is same as the equation for a straight line Y= mx+c

Step-by-step explanation:

The linear equation that describes the relationship between the total monthly cost Y and number of class hours in each month X is the same as the equation of line which is

[tex]Y= mx+c\\\\ Y= 2X+25[/tex]

where Y= the dependent variable, monthly cost

          x= the independent variable, the number of hours for aerobic classes

          c= the intercept, $25

PLEASE HELP ME !!!!!!!!!!

if the distance of load from hinge and spring balance are 35 cm and 15 cm respectively. What is the load weight used if the applied force is 4N ?

Answers

Answer:

The load weight is 2.29 N

Step-by-step explanation:

We note that  at equilibrium, the sum of the moment and the sum of forces about a point is zero, therefore, we have;

∑M =0

∑F = 0

The parameters given are;

The distance of the load from the hinge = 35 cm

The distance of the load from the spring balance = 15 cm

The applied force on the spring balance = 4 N↑

The direction of the applied force on the spring balance = Upwards

Let the weight of the load = W↓

The direction of the weight of the load = Downwards

We use downward negative and upward positive coefficients for the forces

We take moment about the hinge as follows;

Sum of moments equals zero gives;

4 × (35 - 15) - W × 35 = 0

∴ 4 × (35 - 15) = W × 35

4 × 20 = W × 35

W = 4 × 20/35 = 2.29 N

The weight of the load = 2.29 N.

Answer:

The load weight is 2.29 N

hope it helps

Determine what type of model best fits the given stituation. Water leaking from a local reservoir at the rate of 500 gallons per hour.

Answers

Answer:

Well, in the local reservoir we have an initial amount of water A.

And per hour, the amount of water in the reservoir decreases by 500 gals.

So after t hours, the amount of water in the reservoir is:

W = A - 500gal*t

This is a linear equation, so the model that fits best in the given situation is a linear model.

Where the only thing that you need to take in mind, is that the domain of this model is restricted:

This is because we can not have a negative amount of water in the reservoir, so the maximum value of t accepted is:

W = 0 = A - 500gal*t

t = A/500 hours

So the domain of this linear relation is:

t ∈ {0h, A/500 }

Answer: lin

Step-by-step explanation:

Please help me.

List the sides of MNP in ascending order:
m< M = 15, m < N= 75

Answers

Answer:

Take a look at this: https://brainly.com/question/14269575?referrer=searchResults

Step-by-step explanation:

The physician orders 1500 flu injections. There were 300 shots given in September, 450 shots given in October, and 665 shots given in November. What percentage of flu vaccine has been given?

Answers

Answer:

94.33

Step-by-step explanation:

add up all numbers then input into a percentage calculator

Percentage of flu vaccine has been given 94.33%

What is percentage?

Percentage is defined as ratio expressed as a fraction of 100.

The physician have total 1500 flu injections

300 shots given in September,

450 shots given in October,

and 665 shots given in November,

Total flu vaccine has been given = 300+450+665 = 1415

Percentage of flu vaccine has been given = (1415/1500)×100%

Percentage of flu vaccine has been given = 0.9433×100%

Percentage of flu vaccine has been given = 94.33%

Hence, percentage of flu vaccine has been given 94.33%

Learn more about percentage

brainly.com/question/24159063

#SPJ2

On the coordinate plane below, Point P, is located at (2,-3) and point Q is located at (-4,4). Find the distance between points, P and Q

Answers

Answer:

approximately 9.2195

Step-by-step explanation:

We can use Pythagorean theorem

one leg is 7 and the other leg is 6

square them

49 and 36

add

85

square root

approximately 9.2195

Campbells soup company want to create a new sized cam for a new line of soups.If the can holds a volume of 3416.32 cm and the height of the can is 17cm what is the area of the base of the can

Answers

Answer:

200.96cm²

Step-by-step explanation:

Volume of the can is expressed as Length *Breadth* Height.

If the area of the can base is Length * Breadth

Volume of the can = area of the base of the can * Height

Given parameters

Volume of the can V = 3416.32cm³

Height of the can h = 17cm

Required

Area of the base of the can

Substituting the given parameters into the formula we have;

V = Ah

A = V//h

A = 3416.32/17

A = 200.96cm²

Hence, the area of the base of the can is 200.96cm²

Evalute n2+2N for N=5​

Answers

Answer:

Hey there!

Do you mean- [tex]n^2+2n?[/tex]

If so, then your answer would be 5^2+2(5), or 35.

Let me know if this helps :)

in digging a pipe trench that measures 29 feet long, 2 feet 9 inches wide, and 3 feet 6 inches deep.
How many cubic yards of earth were removed from the site?

Answers

Answer:

10.34

Step-by-step explanation:

converting digits to feet,

3ft 6in = 3.5 ft

2ft 9in = 2.75 ft

now feet to yards

3.5ft = 1.16666667 yards (rounded)

2.75ft = 0.9166666667 yards (rounded)

29ft = 9.66666667 yards (rounded)

multiplying them, you'll get approximately 10.34 cubic yards (rounded), that's the volume.

or you can multiply the digits in feet,

3.5×2.75×29

= 279.125 cubic ft

now to convert to cubic yards from cubic ft,

279.125/3³

= 10.337963..

= 10.34 (rounded to the nearest hundredth)

fin the slope of the line that is perpendicular to y=1/3x
1. 3
2. -3
3. -1/3
4. 12

Answers

Answer:

-3

Step-by-step explanation:

When a line is perpendicular, the slope becomes the opposite to the original. If the slope is 1/3, the perpendicular line's slope would be -3.

A rock falls from a tower that is 416 ft high. As it is falling, its height is given by the formula h=416-16t^2. How many seconds will it take for the rock to hit the ground (h=0)?

Answers

5.1 Seconds. t = 5.1

5.1^2 = 26.01

416/16 = 26

26*16 = 416

22/100 simplist form

Answers

Answer:

11/50 is the simplified form of the given expression.

Step-by-step explanation:

22/100

We will cancel the values by the table of 2

11/50 is the simplified form of the given expression.

Hope it will help you :)

11/50

22 divide 2 = 11
100 divide 2 = 50

If JK = 28, JL = 20, KL = 13, and ML = 22, calculate NL. Image not set to scale.

Answers

Answer:

NL  = 440 /13  or 33.85 (to two decimals)

Step-by-step explanation:

Consider triangles JKL and NML

angle JLK = angle NLM           vertical angles

angle KJL = angle MNL           given

Therefore triangles JKL and NML are similar

By proportion of corresponding sides of similar triangles,

NL / JL = LM / LK

Substitute given values

NL / 20 = 22 / 13

solve for NL

NL = 20*22 / 13 = 440 /13  or 33.85 (to two decimals)

Answer:

[tex]\huge \boxed{33.85}[/tex]

Step-by-step explanation:

JL is similar to NL. KL is similar to ML.

We can use ratios to solve.

JL/KL = NL/ML

Let the length of NL be x.

20/13 = x/22

Cross multiply.

13 × x = 22 × 20

13x = 440

Divide both sides by 13.

(13x)/13 =440/13

x = 440/13 = 33.846154...

In XYZ, what is the cosine ratio of X?

Answers

Answer:

c) 12/15 = 4/5

Step-by-step explanation:

imagine we mirror the triangle up, so that Z is on top.

then you can clearly see that 6 is cos(X) times r (and r is then 7.5).

XY is sin(X)×7.5

and again, 7.5 is r (the line making the X angle).

so, the cosine ratio of X is

6 = cos(X)×7.5

cos(X) = 6/7.5 or then 12/15. or simplified 4/5.

yea the person on top is right, bc I also got that correct on my test LMFOAOA

In 2008, golfer Annika Sornestam had a driving accuracy of 71%. That is, on par 4 and par 5 holes, her tee shot landed in the fairway 71% of the time. Explain how to use a spinner to simulate Sorenstam’s performance in a round of golf where she attempts 15 drives. (Hint: What type of chart is a spinner? What does each piece represent?)

Answers

Answer:

Ok, we know that the driving accuracy is of 71%.

Then the first step is to get a spinner that is enumerated from 1 to 100 (in such way that each number is equispaced)

Now, we can mark a section between numbers 1 and 71. (this regio represents the cases where the shot lands in the fairway) and the unmarked region represents the cases where the shot does not land in the fairway.

Now, for each shot, we can spin our spinner next to a fixed pencil, depending on the section of the spinner that is marked by the pencil when the spinner fully stops, we can guess if the shot landed or not in the fairway.

In this way the shot has the region from 1 to 71 (71%) to land in the fairway

and the region from 72 to 100 to not land in the fairway.

If you want to simulate Sorenstam’s performance in a round of golf where she attempts 15 drives, you need to spin the spinner 15 times, and record the oucomes.

What adds to be the bottom numbers but also multiplies to be the top?


39 at the bottom and 25 on the right above 39

Answers

Answer:

well i cant answr it if i oont have more inforomartion

Step-by-step explanation:

Answer:

Step-by-step explanation:

if we add 11,36,61,... to the bottom we get bottom as a multiple of numerator.

Simplify (5x3y) (2xy4)

Answers

Answer: 10x^4y^5

Step-by-step explanation:

5x^3y^1•2x^1y^4

5•2=10

x^3•x^1=x^4

y^1•y^4=y^5

10x^4y^5

If x = a sin teta and y = b cos teta
Find the value of b^2x^2+ a^2y^2


Plssss plsss helppp

Answers

x= a sin theta y=b sin theta

[tex]\\ \sf\longmapsto b^2x^2+a^2y^2[/tex]

[tex]\\ \sf\longmapsto b^2(asin\Theta)^2+a^2(bcos\Theta)^2[/tex]

[tex]\\ \sf\longmapsto b^2a^2sin^2\Theta+a^2b^2cos^2\Theta[/tex]

[tex]\\ \sf\longmapsto a^2b^2(sin^2\Theta+cos^2Theta)[/tex]

[tex]\\ \sf\longmapsto a^2+b^2(1)[/tex]

[tex]\\ \sf\longmapsto a^2b^2[/tex]

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