A, B and C start at the same time in the same direction to run around a circular stadium. A completes a round in 252 sec, B in 308 sec and C in 198 sec, all starting from the same point. After what time will they again meet at the stating point again ?

A. 46 min 12 sec

B. 45 min

C. 42 min 36 sec

D. 26 min 18 sec

Answer: Option A

Solution(By Examveda Team)

Time taken by A
= 252 sec
= 2² ×3² ×7
Time taken by B
= 308 sec
= 2² × 7 × 11
Time taken by C
= 198 sec
= 2 × 9 × 11
Together will meet at starting point :
= L.C.M. (252, 308, 198)
= 2² × 3² × 7 × 11 sec
So, required time (minutes)
$$\eqalign{ & {\text{ = }}\frac{{4 \times 9 \times 7 \times 11}}{{60}} \cr & = 46\min 12\sec \cr} $$