Question

A hare completes a straight 300-meter downhill run in t seconds and at an average speed of (x + 10) meters per second. The hare then cycles up the mountain (the same distance) at an average speed of (x - 8) meters per second. If the ride up the mountain took 135 seconds longer than its run down the mountain, what was the hare's average speed, in meters per second, during its downhill run?

• A. 10
• B. 15
• C. 20
• D. 25

Answer 1

The correct option is C

20

Approach : Reverse gear
Since the difference in time is given, and

$Time=\frac{Distance}{Speed}$

$\frac{300}{x-8}-\frac{300}{x\pm 10}=135$

Now going from answer options, we can easily substitute and see which value satisfies this equation. Option (c) is the correct answer choice.