The average age of a class is 15.8 years. The average age of the boys in the class is 16.4 years

The average age of a class is 15.8 years. The average age of the boys in the class is 16.4 years while that of the girls is 15.4 years. The ratio of boys to girls in the class is
(a) 3:5
(b) 2:3
(c) 3:4
(d) 1:2

Anurag Mishra Professor Asked on 26th March 2016 in Maths.
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  • 1 Answer(s)

    Answer: (b) 2: 3

    Explanation:-
    let x = number of girls
    y = number of boys
    sum of girls ages / x = 15.4
    sum of boys ages / y = 16.4
    The sum of the girls’ ages is 15.4x, and boys’ sum is 16.4y
    (sum of girls ages + sum of boys ages) / (x+y)= 15.8
    (15.4x + 16.4y) / (x+y) = 15.8
    15.4x + 16.4y = 15.8(x+y)
    15.4x + 16.4y = 15.8x + 15.8y
    0.6y = 0.4x
    0.6y/x = 0.4
    y/x = 0.4/0.6
    Then, The ratio of boys and girls = 2: 3.

    Hence, the correct answer is option (b) 2: 3.

    Anurag Mishra Professor Answered on 26th March 2016.
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