SAT - Problem Solving - Question of the Day

Three lighthouses are visible from the promenade at Rivermouth. One flashes every 1½ minutes, another flashes every 2 minutes, and the third flashes every 50 seconds.

All three have just flashed at the same time.

How long will it be before they all flash at the same time again?

A. 6.0 minutes

B. 7.5 minutes

C. 10.0 minutes

D. 30.0 minutes

E. 150.0 minutes