Question

five bells beginning together toll at intervals of 4,5,7,8 and 10s respectively after what interval of time will they toll again together

Answer 1

The interval at which they will toll again
= L.C.M of 4,5,7,8,10

4 = 2×2
5 = 5
7 = 7
8 = 2×2×2
10 = 2×5

L.C.M
= 2×2×2×5×7
= 280
-----------------------------
Hence after 280 sec = 4 min 40 sec ,the bells will toll again.

Answer 2

Answer:

After 280 sec. time interval.

Step-by-step explanation:

Given five bells beginning together toll at intervals of 4,5,7,8 and 10s

The interval at which they will toll again is least common multiple (L.C.M) of 4,5,7,8,10

Factorization of 4 = 2×2

Factorization of 5 = 5×1

Factorization of 7 = 7×1

Factorization of 8 = 2×2×2

Factorization of 10 = 2×5

L.C.M = 2×2×2×5×7

         = 280 sec.

So after 280 sec. time interval all five bells will toll again.