Question 56

There are 150 students in a school. If the ratio of the number of boys to girls is 4 : 1, then what is the mean proportion between the number of boys and girls in the school?

Solution

Total students = 150

Ratio of boys to girls = 4 : 1

that is (4y+y) = 5y = 150

y = $$ \frac{150}{5} = 30 $$

Number of boys = 4y = $$ 30 \times 4 = 120 $$

Number of girls = y = $$ 30 \times 1 = 30 $$

Mean proportional between two numbers is the square root of the product of the two numbers

Mean proportional of 120 and 30 = $$ \sqrt(120 \times 30)$$ = $$\sqrt(3600) = 60 $$

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