Find out The Age of The Youngest Boy.

The average age of 3 boys is 30 years and the ratio of their ages is 3: 5: 7. Find out the age of the youngest boy.

  1. 16 years
  2. 12 years
  3. 15 years
  4. 18 years
Anurag Mishra Professor Asked on 7th September 2015 in Maths.
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1 Answer(s)

Answer: (4) 18 years

Explanation:-
The average age of 3 boys = 30 years
Then, the sum of the age of 3 boys = 3 x 30 = 90 years

The ratio of their age = 3: 5: 7.
Let the age of their be 3X, 5X and 7X.
Then, 3X + 5X + 7X = 90
15 X = 90
X = 90/15
X = 6

Then, the age of youngest boy is 3X = 3 x 6 = 18 years.

Hence, the answer is (4) 18 years.

Anurag Mishra Professor Answered on 9th September 2015.
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