Question

5. The average age of 3 sisters is 15. If the ages of 2
sisters are 12 years and 15 years, the age of the third
sister is
(A) 21 years
(B) 17 years
(C) 18 years
(D) 16 years​

Answer 1

Answer:

18 years

Step-by-step explanation:

The average age of three sisters is 15

Sum of age of three sisters = average age × no. of sisters

Sum of age of three sisters = 15 × 3 = 45 years

The age of two sister is 12 and 15.

Sum of age of two sisters = 12 + 15 = 27 years

Age of third sister = 45 - 27 = 18 years

Answer the age of third sister is 18 years

Now checking the correctness of answer by taking their average

Average = (18 + 12 + 15)/3

15 = 45/3

15 = 15

Means answer is correct.

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Answer 2

Answer:

18 years. hope it helps you