SOLUTION: The telephone poles along a road are 20m apart and a car travels from the first to the fifteenth in 10½ seconds. Calculate the speed of the car in km/h.

Algebra ->  Conversion and Units of Measurement -> SOLUTION: The telephone poles along a road are 20m apart and a car travels from the first to the fifteenth in 10½ seconds. Calculate the speed of the car in km/h.      Log On


   

Question 1205404: The telephone poles along a road are 20m apart and a car travels from the first to the fifteenth in 10½ seconds. Calculate the speed of the car in km/h.
Found 2 solutions by math_tutor2020, ikleyn:
Answer by math_tutor2020(3817) About Me  (Show Source):
You can put this solution on YOUR website!

Ignore my previous answer. I misread the question.

Answer by ikleyn(52787) About Me  (Show Source):
You can put this solution on YOUR website!
.
The telephone poles along a road are 20m apart and a car travels from the first
to the fifteenth in 10½ seconds. Calculate the speed of the car in km/h.
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From the first to the 15-th telephone pole, there are 15-1 = 14 intervals ( ! not 15 ! ).


Therefore, the distance from the first to the 15-th telephone pole is  20*14 = 280 meters  ( ! not 300 meters ! ).


The speed of the car is the distance divided by the time

    speed = 280%2F10.5 = 262%2F3 m/s.


In kilometers per hour, this speed is

    %28280%2F10.5%29%2A%283600%2F1000%29 = 96 km/h.


ANSWER.  The speed of the car is 96 km/h.

Solved.

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The lesson to learn from my post is that if n points are uniformly/equidistantly
placed on a straight line, then there are (n-1) equal intervals between them.

This problem is specially designed/intended to teach students to this wisdom.