Nicky and Cristina are running a race. Since Cristina is faster than Nicky, she gives him a 36 meter head start. If

[VJesus12]

Nicky and Cristina are running a race. Since Cristina is faster than Nicky, she gives him a 36-meter head start. If Cristina runs at a pace of 5 meters per second and Nicky runs at a pace of only 3 meters per second, how many seconds will Nicky have run before Cristina catches up to him? (Note: 36-meter head start means that Nicky begins running from a location that is 36 meters ahead of Christina's location.)

(A) 15 seconds
(B) 18 seconds
(C) 25 seconds
(D) 30 seconds
(E) 45 seconds

Answer: B

Source: Manhattan GMAT

[Brent@GMATPrepNow]

Nicky and Cristina are running a race. Since Cristina is faster than Nicky, she gives him a 36-meter head start. If Cristina runs at a pace of 5 meters per second and Nicky runs at a pace of only 3 meters per second, how many seconds will Nicky have run before Cristina catches up to him? (Note: 36-meter head start means that Nicky begins running from a location that is 36 meters ahead of Christina's location.)

(A) 15 seconds
(B) 18 seconds
(C) 25 seconds
(D) 30 seconds
(E) 45 seconds

Answer: B

Source: Manhattan GMAT

In 1 second, Nicky runs 3 meters, and Christina runs 5 meters.
So, in ONE SECOND the gap between Nicky and Christina decreases by 2 meters.

At the beginning, the gap between them is 36 meters. So, since (18)(2) = 36, we can see that it will take 18 seconds for the 36-meter gap to reduce to zero meters.

Answer: B

Cheers,
Brent