Question

In a 200 metres race A beats B by 35 m or 7 seconds. A’s time over the course is?
A) 40 sec
B) 47 sec
C) 33 sec
D) None of these

Answer 1

Hint:First find out the time taken by B and it is given that A beats B by 7 sec, so A’s Time = B’s time – 7 sec;

Complete step-by-step answer:
It is given that A beats B by 35m or 7 seconds.
It implies B covers last 35m race in 7 seconds, now we will find the time taken by B to complete the 200m race.
Apply the formula, $speed = \dfrac{{dis\tan ce}}{{time}}$
Numerically, it can be expressed as $s = \dfrac{d}{t}$
d = 35m and t = 7sec
Now, If B covers 35m in 7 sec
He covers 1m in $\dfrac{7}{{35}}$sec
So, B will complete the race of 200m in time = $$\dfrac{{7 \times 200}}{{35}}$$= 40 Sec
Total Time taken by B to complete the whole race of 200 m = 40 sec
Since A beats B and B loses the race by 7 sec that means A has completed the race 7 sec before B
Now, we will find A’s time over the course = 40-7 sec = 33 sec.

Note:
Find the time taken by B to cover 200m, since he had completed 35m in 7 sec so, from this we can find the total time taken by B to complete 200m race.