Question

Two cars , car x and car y are at thr same starting point of a 2 km track at the same time .car x make one lap every 60 s and every 80 s respectively. i ) how long , in seconds , will it take for both cars to be back at the starting point at the same time ? ii ) how long , in minutes , will it take for the faster car to be 5 laps ahead of slower car ?

Answer 1

both will meet again at start point after LCM(60,80) seconds.
That is 240 seconds.
in time slower car completes one lap, faster one covers 1 +20/80 lap, that is 1.25 laps. After 20 laps faster by slower car car will be 5 laps ahead, time =20*60 =1200s =20 minutes