Question

There are x boys playing in the park. The number of girls playing in the park is equal to the square root of the number of boys. If the total number of boys and girls playing in the park is 42, find the number of boys. A. 49 B. 7 C. 36 D. 6

Answer 1

C 36.

Explanation:

If x is the number of boys then √x is the number of girls.

x + √x = 42

√x = 42 - x

Squaring both sides:

x = (42 - x)^2

1764 - 84x + x^2 - x = 0

x^2 - 85x + 1764 = 0

(x - 36)(x - 49) = 0

x = number of boys = 49 or 36.

But the total number = 42 so there must be 36 boys. Also √36 = 6 so the answer is 36 boys.