Question: A, B, C are running around a circular park. They start at the same point. A overtakes C, 3 times for every round that C makes. C overtakes B, 6 times for every round that B makes. What is the ratio of A's speed to that of B?

A: 9:2
B: 18:1
C: 28:1
D: 21:1

Ans: C
Solution: As A overtakes C three times , A's speed must be four times of C
and C speed is 7 times more than B
A=4C
B=C/7
therefore
A/B=28:1