Jack rides in a motorboat against a river current for 36 km. Then he returns to his starting point by floating down river on a raft. Tommy travels 9 hours less on the motorboat than on the raft. Find the speed of the river current if the speed of the motorboat in still water is 15 km/h.

Answers

Answer 1

Answer:

  3 km/h

Step-by-step explanation:

You want to know the speed of the river current if floating 36 km downstream takes 9 h longer than the trip upstream in a boat with a speed relative to the current of 15 km/h.

Time

The relation between time, speed, and distance is ...

  time = distance / speed

If c represents the speed of the current, then 15-c is the speed upstream. The relation between the travel times is ...

  36/(15 -c) = 36/c -9

Solution

Multiplying by c(15-c), we have ...

  36c = 36(15 -c) -9(c)(15-c) . . . . . . . multiply by c(15-c)

  36c = 540 -36c -135c +9c² . . . . . eliminate parentheses

  9c² -207c +540 = 0 . . . . . . . collect terms

  c² -23c +60 = 0 . . . . . . . . divide by 9

  (c -20)(c -3) = 0 . . . . values that make the factors zero are c=20, c=3

The speed of the current is 3 km/h.

__

Additional comment

The speed of the current cannot be greater than 15 km/h, or the boat could not go upstream. The speed of the current cannot be greater than 4 km/h, or the trip downstream would take less than 9 hours.

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Related Questions

I really need help to understand this problem for my end of course exam!!!!

Answers

Answer:

D. [tex]13(2.81)^n[/tex]

Step-by-step explanation:

[tex]13(1.09)^{12n} < ==exponents\ first\(PEMDAS)\\\\13(2.8126)^n < ==approximate\\\\13(2.81)^n[/tex]

Hope this helps!

Triangle ABC is graphed. (image included)
1) Transform triangle ABC using the rule (x,y) → (-x,y)
2) Describe the transformation precisely.

Answers

Answer:

see attachedthe figure is reflected in the y-axis

Step-by-step explanation:

1.

The given transformation moves each point horizontally to the same distance on the other side of the y-axis. This is shown in the attachment.

__

2.

The given rule ...

  (x, y) → (-x, y)

is the most precise description of the transformation. In English, it can be described as a reflection in the y-axis.

Polygon ABCD has the following vertices a (-3,3), B(5,5), C (5, -4) and D (-3, -4) calculate the area of the polygon.

Answers

Answer:

64 units squared

Step-by-step explanation:

If you put the points on a graph you can see the shape is a trapezoid. The left and right sides are the bases, the bottom is the height. The area formula is to average the bases and times by the height. see image. You could do a lot of distance formula and slope calculations, but on the graph you can count the squares to find side lengths.

If 8 parts take 20 minutes to make, how many minutes does it take to make 6 parts?

Answers

Answer: 15 mins

Step-by-step explanation:

20 ÷ 8 = 2.5 (how many Mins 1 part takes)

2.5 x 6 = 15

It will take 15 minutes does it take to make 6 parts.

What is the unitary method?

The unitary method is a process by which we find the value of a single unit from the value of multiple units and the value of multiple units from the value of a single unit.

If 8 parts take 20 minutes to make then 1 part take x time which is equal to;

[tex]\rm x=\dfrac{20}{8}\\\\x= 2.5 \rm \ minute[/tex]

One part takes 2.5 minutes.

The minutes does it take to make 6 parts are;

[tex]= 6 \times 2.5\\\\=15[/tex]

Hence, it will take 15 minutes does it take to make 6 parts.

To know more about the unitary method click the link given below.

https://brainly.com/question/13823511

#SPJ4

m exponent 2 plus 15 if m =4​

Answers

Answer:

31

Step-by-step explanation:

[tex]4^{2}[/tex]=16

16+15=31

I’m stuck, HELP

3(6) + 4(2)^3 - 5

Answers

Answer:

45

Step-by-step explanation:

Lets split the problem then add/subtract at the end

3 x 6 = 18

Due to Order of operations we do 2^3 first then multipy by 4

so 2^3 = 8 Then we do 8 x 4 = 32

Now we add/subtract

18 + 32 - 5 = 45

45 is the answer

Answer:

45

Step-by-step explanation:

Parenthesis

Exponents

Multiplication

Division

Addition

Subtration

[tex]3(6) + 4(2)^3 - 5 < ==multiply\ the\ exponents\ first\\\\18+4(8)-5 < ==multiply\ first\\\\18+32-5 < ==addition\ before\ subtraction\\\\50-5 < == subtract\\\\45 < == final\ answer[/tex]

Hope this helps!

Find the mean of the following data set: 20, 22, 24, 25, 29, 30, 32, 36​

Answers

27.25 because you add up all of the numbers than divide them by the number of numbers which is 8

Answer:

27.25

Step-by-step explanation:

we find the mean by adding all the values and dividing by the number of values.

answet please and please show work

Answers

Answer:

4, 3, 4

Step-by-step explanation:

The unsimplified ratio of squares to triangles is 6:8, which simplifies to 3:4. That means, for every 3 squares, there are 4 triangles

As stated above, the simplified ratio of squares to triangles is 3:4

2/3 x 12 write in simplest form.

Answers

2/3 ×12

= 2/1 × 4

= 2× 4

=8

........

Question 9 of 12
What is cos 60°?
A. 13
B. 1
C.
2
D.
2.
E.
NS-
F. V

Answers

The answer is D 1/2
Cos of 60 = 0.5
Which 0.5 as a fraction is 1/2

Answer:

D

Step-by-step explanation:

You can find the answer by memorizing the values of the unit circle.

32 divided by 10-8 divided by 2-3

Answers

Answer:

-3.8

Step-by-step explanation:

32÷10-8÷2-332÷10-4-33.2-4-33.2-7-7.0-3.2-3.8answer

The expression "32 divided by 10-8 divided by 2-3" evaluates to -3.8.

To solve the expression "32 divided by 10-8 divided by 2-3," we follow the order of operations, which is often represented by the acronym PEMDAS (Parentheses, Exponents, Multiplication and Division from left to right, and Addition and Subtraction from left to right).

32 divided by 10 equals 3.2.

Next, perform the second division which is 8 divided by 2 which equals 4.

Subtract the result of the second division (4) from the first division result (3.2): 3.2 - 4

= -0.8.

Finally, subtract 3 from the -0.8.

-0.8 - 3

= -3.8.

Therefore, the expression "32 divided by 10-8 divided by 2-3" evaluates to -3.8.

To learn more on Expressions click:

https://brainly.com/question/14083225

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What is 8 * 8?
8*8 =
A. 64
B. 24
C. 91
D. 8

Answers

Answer: A. 64

Step-by-step explanation:

8 + 8 + 8 + 8 + 8 + 8 + 8 + 8 = 64

According to einstein, nothing in the universe can move faster than which approximate speed? 1.0 × 107 m/s 1.0 × 108 m/s 3.0 × 108 m/s 3.0 × 109 m/s

Answers

The speed of light is 3.0 ×108m/s.

We have ask about the theory of Albert Einstein,

According to einstein, nothing in the universe can move faster than light

What is the speed of the light?

Albert Einstein said that nothing travels faster than the speed of light, and the speed of light is

[tex]3.0\times108 m/s[/tex]

So that the nothing can travels faster than the speed of light.

light travels with very high speed.

Therefore we get the correct option is 3.

That is the speed of light is 3.0 ×108m/s.

To learn more about the speed of light visit:

https://brainly.com/question/104425

What is the value of x in the figure?


Enter your answer in the box.


x =

Answers

Answer:

68 degrees

Step-by-step explanation:

The straight horizontal line is a straight angle with 180 degrees it is split in a way that you know under the right angle, is another right ange making up part of the 180° line, add 22 and then subtract what you get from 180 to get 68.

A simpler way, add the angles in the X and 22 degree things and there is a right angle, 90 degrees, subtract 22 from 90 and get 68

Two different ways, either will work

Hope this helps!

Angles are complementary

x+22=90x=90-22x=68

x is 68°

can someone send the answer that on the picture and show your work

Answers

Answer:

k = 52

Step-by-step explanation:

- 8 = [tex]\frac{k-4}{-6}[/tex] ( multiply both sides by - 6 to clear the fraction )

48 = k - 4 ( add 4 to both sides )

52 = k

Answer: k=52

Step-by-step explanation:

-8= k-4/-6

multiply by -6

48=k-4

add 4 to both sides

k=52 :)

The point (6, - 5) is reflected across the y axis what is the new point

Answers

Answer:

  (-6, -5)

Step-by-step explanation:

Reflection across the y-axis leaves the point on the same horizontal line, but with the sign of its x-coordinate changed.

  (x, y) ⇒ (-x, y) . . . . . reflection across the y-axis

  (6, -5) ⇒ (-6, -5)

The image point is (-6, -5).

please help

The table below shows the number of hours that a
scientist has been observing bacteria in a petri dish

Answers

Answer:

In the beginning there were 20 bacterias in the petri dish.

For each of the figures, write an absoulute value equation that has the following solution set.

Answers

The solution set -18 and 0 are the true values of the absolute value equation

The absolute value equation that has the a solution set of -18 and 0 is |x + 9| = 9

How to determine the absolute value equation?

From the figure, the solution sets of the absolute value equation are given as:

x = {-18, 0}

Calculate the mean of the solution set

Mean = 0.5 * (-18 + 0)

Mean = -9

Calculate the difference of the solution set divided by 2

Difference = (0 + 18)/2

Difference = 9

The absolute value equation is the represented as:

|x - Mean| = Difference

Substitute known values

|x + 9| = 9

Hence, the absolute value equation that has the a solution set of -18 and 0 is |x + 9| = 9

Read more about absolute value equation at:

brainly.com/question/2166748

Answer:

|x+9|=9

Step-by-step explanation:

Brainlest if u get it right​

Answers

Answer:

A. would be best I'm pretty sure

Step-by-step explanation:

Answer: A.

Step-by-step explanation: With this option, everyone in that middle school is involved, and not just eighth-graders, math club students, or detention students.  Option A is a unbiased sample, therefore, that's your answer.

Hope this helps! :)

Asia has a jar of marbles. She randomly selects a marble from the jar, records its color, and returns it to the jar. She repeats this 74 times. Her results are shown in the table. A frequency table shows each outcome and its frequency. Red, thirteen times. Blue, twenty times. Green, twenty-two times. Yellow, nineteen times. What is the experimental probability of Asia choosing a green marble?

Answers

Answer:Experimental probability = 0.297

Step-by-step explanation: experimental probability = number of times event occurs/total number of trials
Probability = 22 divided by 74 = 0.297

Therefore the experimental probability of choosing green marble is 0.297.

Fisher Auto Parts is running a 45% clearance sale on batteries. One battery cost $149.99. If the consumer purchases 2 batteries. What would be the final cost?
Sales tax is 5%.

Answers

Answer:

$204.74

Step-by-step explanation:

At 45% off each battery, the price for 1 battery would be (149.99)*(0.65) = $94.50.  Two batteries would be a total of $194.99.

Add 5% tax:

($194.99)(1.05) = $204.74

Pls help ill give 15 brainliest and 5 starts question is down below

Answers

Answer:

Area of right angle triangle is axb/2

3x4/2 = 6 sq. Cm

Area of parallelogram = bxh

20x21.5 = 430 in2

Answer:

Area of the triangle: 6 cm
Area of the parallelogram: 430 in²

Step-by-step explanation:

Area of a triangle formula is base * height * 1/2, in this case 4 * 3 * 1/2, which equals 6.

Area of a parallelogram formula is base * height, in this case 21.5 * 20 which equals 430.

Help pleazeeeeee! I need this as soon as possible

Answers

It is the second option


Andrea Spent a total of $.43.87 on now clothes at a department store bought one pair of Sandals for $8. One T-shirt for 9.49 and two Jeans The tax on the purchase was $2.88 How much did Andrea pay for one pair of jeans, if each pair costs the same amount.

Answers

Answer:

$11.75

Step-by-step explanation:

We need to first subtract to find our answer :)

43.87 - (8 + 9.49 + 2.88)

43.87 - 20.37

23.50

Now we divide :)

23.50/2 = 11.75

Have an amazing day!!

Please rate!!

Let x, y, and z represent three rational numbers, such that y is 512 times x and z is 50.25 more than x. If y=15.5, what is the value of z?
Z=

Answers

The value of z is 15.5 so b I just answered this

Please help with angle addition

Answers

Angle BAD is equal to angle 1 plus angle 2 which is equivalent to 32 + 29 = 61 degrees
Pretty sure the angle is 61°

Hope this helped!!

Multicultural Studies!
HELP PLEASE

Gisela didn't say anything when her friend made a joke about the texture of
Black people's hair. What is Gisela showing?
O A. Assertive behavior toward racism
B. Institutional racism
C. Passive acceptance of racism
D. Intolerance toward racism

Answers

Answer:

It is Passive acceptance of racism, There was no reason why she needed to say black people unless she wanted to downplay them. She is being racist because she saying that only black people have this type of texture. If her friend made a joke like this then she would do worse jokes like calling black people monkeys (aka N's that the definition of the N-word monkey).

If two men walk in opposite directions for 8 meters then turn left and walk six meters how far apart are they

Answers

Answer:

20 meters

Step-by-step explanation:

Solve this problem please and thank you.

Answers

Answer:

  B

Step-by-step explanation:

The given expressions can be compared by putting each in standard form.

A. -8 -7n +16n = (-7+16)n -8 = 9n -8

B. 9(n -8) = 9n -72 . . . . different from the others

C. n -8 +8n = (1 +8)n -8 = 9n -8

D. 9n -8

_____

The standard form of a polynomial expression has the variable terms in decreasing order by degree

Two angles are supplementary angles.
One angle measures 58°. The other angle
measures (3n + 5)º What is the value of n?

A.) 9

B.) 32

C.) 39

D.) 122

Answers

a is the answer because it makes sense and it's very logical

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