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ASHA 777 [7]
2 years ago
13

12. A cyclist travels 40 km at a speed of x km/h. Find the time

Mathematics
2 answers:
GREYUIT [131]2 years ago
7 0

Answer:

Step-by-step explanation:

distance = rate times time, so

           

           distance

time = --------------

               rate

Here the distance is 40 km and the rate is x.  Then

              40 km

time = --------------  =  (40/x) hr

             x km/hr

If the speed is reduced by 2 km/hr, we get:

              40 km                                            40 km                  40

time = -------------------------------  or time = ----------------------- = --------- hr

             (x km/hr - 2 km/hr)                      (x - 2) (km/hr)       x - 2

The difference between the times is:

 40          40

-------- - --------- = 1 hr          Solve this for the original speed, x

x - 2         x

40x - 40x + 80                                80

-----------------------  =  1 hr     or     ------------ = 1     or 80 = x^2 - 2x

     x(x - 2)                                     x(x - 2)

Rewriting this in standard quadratic form:  x^2 - 2x - 80 = 0

Here a = 1, b = -2 and c = -80, and so the discriminant b^2 - 4ac is:

(-2)^2 - 4(1)(-80) = 324

The solutions are:

   

      -(-2) ± √324       2 ± 18

x = -------------------- = ------------ = 1 ± 9, or 10 (discard the other root)

              2                      2

The original speed was 10 km/hr

Ket [755]2 years ago
4 0

the answer is 10 km/hr.

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Savatey [412]

Complete question is;

Zac and Lynn are each traveling on a trip. So far, Zac has traveled 123.75 miles in 2.25 hours. Lynn leaves half an hour after Zac. So far

she has traveled 105 miles in 1.75 hours. Assume Zac and Lynn travel at constant rates.

Let a represent the number of hours that have elapsed since Zac started traveling. Let y represent the number of miles traveled. Write a system of linear equations that represents the distance each of them has traveled since Zac left on his trip.

Assume Zac and Lynn continue to travel at the same constant rates and make no stops.

Determine the solution of the system of linear equations.

Answer:

Zac: y = 55a

Lynn: y = 60(a - ½)

6 hours after Zac started traveling, both Zac and Lynn would have covered 330 miles each.

Step-by-step explanation:

Zac has traveled 123.75 miles in 2.25 hours. Since he travels at constant speed, we can say;

zac's speed = 123.75/2.25 = 55 mi/hr

Similarly, Lynn traveled 105 miles in 1.75 hours. Thus, since she travels at a constant speed;

Lynn's speed = 105/1.75 = 60 mi/hr

Now, we are told that a represents the number of hours that have elapsed since Zac started traveling and y represents the number of miles traveled.

Thus;

a hours after Zac started travelling, his distance covered will be;

Zac: y = 55a

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Thus, Lynn's distance traveled after Zac started = 60(a - ½)

Lynn: y = 60(a - ½)

The solution will be when they have travelled equal distances a hours after Zac started. Thus;

55a = 60(a - ½)

55a = 60a - 30

60a - 55a = 30

5a = 30

a = 30/5

a = 6 hours

Putting 6 for a in y = 55a, we have;

y = 55 × 6

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2 years ago
Mr. Wilson is giving his students a vocabulary test tomorrow over all the terms they have learned from this semester. Today, he
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1) The population

Is the set of all the terms that the teacher taught this semester and which he wrote down on the note cards and put in the paper bag.

2) The sample is every set of five cards that is selected by each student.

3) I think the sample is representative because all ther terms have the same probability of being selected. 

Further, given that the cards are replaced every time all the students will face the same population when they are going to select a sample.
<span><span>Comments </span> <span>Report</span></span>
8 0
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Tyler plans to snowboard for 7 days. A daily ticket costs $50, but there is a
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Answer:

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Sammie bought just enough fencing to border either a rectangular plot or a square plot, as shown. The perimeters of the plots ar
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Perimeter of square : p = 4a.....
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perimeter of rectangle : p = 2(L + W)
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Which graph shows data whose r-value is most likely closest to 1?
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Answer:

B on ed 2020

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