question_answer

Three bells toll together at intervals of 9, 12 and 15 minutes. If they start tolling together, after what time will they toll together again?

A)  \[1\,hr\]                             

B)         \[1\frac{1}{2}hrs\]

C)  \[2\frac{1}{2}hrs\]         

D)         \[3\,hrs\]