Question

Suppose two cars are racing on a circular track one kilometer in circumference. The first car can circle the track in 15 seconds at top speed while the second car can circle the track in 12 seconds at top speed. How much lead does the first car need starting the last lap of the race not to lose? 

 (A) at least 250 m 

(B) at least 83 m 

(C) at least 200 m 

(D) at least 67 m 

(E) at least 104 m 

Answer 1

Correct option (A) at least 250 m

When the first car starts the last lap, it will finish the race in 15 seconds from that point. In 15 seconds, the second car will travel (1 km/12s) × 15s = 1250m so the first car must be at least 250m ahead when starting the last lap to win the race.