Question

THREE BALLS RING AT INTERVALS OF 12,15 AND 21 MINUTES IF THEY RING SIMULANTANEOUSLY AT 9 AM THEN NEXT

Answer 1

Answer:

4 PM

Step-by-step explanation:

PART 1

LCM of three numbers must be taken.

Let us use prime factorization in this case

• Write out the prime factors of each number

12: 2 x 2 x 3

15: 3 x 5

21: 3 x 7

•Cancel out the common factors

We will be left with:

2 x 2 x 3 x 5 x 7

• Multiply the remaining factors

2 x 2 x 3 x 5 x 7 = 420

:- 420 minutes

PART 2

• Convert minutes to hours

420/60

= 7

• Add the hours to the final time

9 AM + 7 hours

= 16 hours

= 4 PM

«» The three bells will ring simultaneously at 4 pm