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3 clock bells ring at an interval of 60 sec, 90 sec, 125 sec. If they ring together at 1 PM then at what time will they ring together again?

3 clock bells ring at an interval of 60 sec, 90 sec, 125 sec. If they ring together at 1 PM then at what time will they ring together again? Correct Answer 2 : 15 PM

GIVEN:

3 clock bells ring at an interval of 60 sec, 90 sec, 125 sec.

CONCEPT:

LCM: It is a number which is a multiple of two or more numbers.

CALCULATION:           

They will run together after LCM of (60, 90 and 125)

We need to get the LCM of all 3 numbers i.e. 60, 90 and 125

We can factorize the numbers:

60 = 2 × 2 × 3 × 5

90 = 2 × 3 × 3 × 5

125 = 5 × 5 × 5

So,

LCM (60, 90, 125) = 2 × 2 × 3 × 3 × 5 × 5 × 5 = 4500

They all 3 clock bells ring together again after 4500 seconds.

⇒ 1 PM + 75 minutes = 2 : 15 PM

∴ they will ring together at 2 : 15 PM

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