P, Q and R start running around a circular track and complete one round in 18, 22 and 30 seconds, respectively. In how much time will they meet again at the starting point?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e 16 min 30 sec.
P =18 seconds
Q = 22 seconds
R = 30 seconds
Prime factorization:
18 = 2 × 3 × 3
22 = 2 × 11
30 = 2 × 3 × 5
LCM = 2 × 3 × 3 × 5 × 11 = 990 or (16 minutes and 30 seconds)