4 Bells toll together at 11:00 A.M. They toll after 7, 8, 10 and 18 se
| 4 Bells toll together at 11:00 A.M. They toll after 7, 8, 10 and 18 seconds respectively. How many times will they toll together again in the next 4 hours?
A. 3
B. 4
C. 5
D. 6
Right Answer is: C
SOLUTION
There are 4 Bells toll together at 11:00 A.M. They toll after 7, 8, 10 and 18 seconds respectively.
We will first calculate LCM of 7,8,10,18
7 = 1×7
8 = 2×2×2
10 = 2×5
18 = 2×3×3
LCM (7,8,10,18) = 7 × 2 × 2 × 2 × 5 × 3 × 3 = 2520 seconds = 42 mint
So they will toll together after every 42 mint.
Now we are interested in finding that how many times will they toll together again in the next 4 hours
4 hours = mint
No of times they will troll together in next 4 hours = = 5 times
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4 Bells toll together at 11:00 A.M. They toll after 7, 8, 10 and 18 se