# Question

A group of children consists of 11 girls and 5 boys. The average height of the group of children is 122.5cm. The average height of the girls is 3.2cm more than the average height of the boys. Find the average height of the girls.

TIA!

I would solve the question as follows :

11 + 5 = 16 (number of children)
16 x 122.5 = 1960 (total height of the 16 children)
11 x 3.2 = 35.2 (total height of girls more than total height of boys)
1960 – 35.2 = 1924.8
1924.8/16 = 120.3 (average height of the boys)
120.3 + 3.2 = 123.5 (average height of girls)

Ans : 123.5 cm.

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Total height:                       122.5 x (11+5) = 1960

Average w/o diff:               1960 – (11 x 3.2) = 1924.8

Average height (Boy):      1924.8 / 16 = 120.3

Average height (Girl):      120.3 + 3.2 = 123.5 cm

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You may wish to use the unit x part method which is the best method for this question.

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122.5 x 16 = 1960

3.2 x 11 = 35.2

1960 – 35.2 = 1924.8

1924.8 / 16 = 120.3

120.3 + 3.2 = 123.5

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This is a Quantity Amount question.

 Boy Girl Total Quantity 5 11 16 Each 1u 1u + 3.2 122.5 Product 5u 11u + 35.2 1960

5u + 11u  + 35.2 = 1960

16u = 1960 – 35.2

16u = 1924.8

1u = 120.3

120.3 + 3.2 = 123.5

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Just another alternative.

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