Races problem #1

[papgust]

"A can give B a start of 20 seconds in a km race. B can give a start of 30 seconds in the same race. If A can give a start of 200m in the race, how long will A take to run the km?"

Can someone give a good approach to this prob?

[KapTeacherEli]

I'm afraid I'm not parsing this problem well--are you summarizing it? If so, can you post the original question?

[papgust]

Hi Eli,

This is the original qn. I have not missed a single word..

[real2008]

please mention the source of question...

[papgust]

Hi,

I got this kind of a problem from one of my friends who is preparing for CAT.

[vidyadhar]

if Va, Vb are speeds of A and B. And t is the time for A to complete the Km race.

Vb (t + 20) = Va*t

Vb(t-30)+ 200= Va*t.

Solving above 2 eqns for Vb, we get Vb= 4 m/s

Since it is a km race (1 Km).
Vb(t + 20) =1000 m = 4 (t + 20) => t=230 s

so the time for A to complete a km is 230 Seconds.

Not sure if it is the best/correct approach.