Previous Year Questions

Here

Atul's speed as A m/s

Vishu's speed as V m/s

Let:-

Time taken by Atul to cover 900m as Ta seconds

Time taken by Vishu to cover 900m as Ty seconds

Atu's speed:

900/T_a

Vishu's speed in the first race;

765/ T_a +20

vishu's speed in the second race: 711/T_a+8

Equating the two speeds:

765/ T_a +20=711/T_a+8

Multiply both sides by (Ta + 20)(Ta +8) to eliminate the denominators;

765(T_a+8)=711(T_a+20)

Expanding both sides;

765T_a+6120=711T_a+14220

Now, subtract 711T_a from both sides:

765T_a-711T_a=14220-6120

54T_a=8100

T_a= 150 seconds

Atul takes 150 seconds to run the full race.

Now, let's find Vishu's time:

Using the equation for Vishu's speed in the first race:

765/ T_a+20=765/150+20=765/170=4.5m/sec

Vishu's speed:V=4.5m/s

170

Now, calculate Vishu's time to run 900m:

T_v=900/4.5=200sec

T = 200 seconds i.e 3 minutes 20 seconds ::Vishu will complete the full race in 3 minutes 20 seconds.

Option (c) is the correct answer.