Question 60641
8T^2 = (pi)^2 L

Given L = 10 feet

Plugging in this value in the above equation..
8T^2 = (pi)^2(10)
8T^2/8 =  (pi)^2(10)/8
==> t^2 = (pi)^2(5/4)
Taking square root on both the sides..
T = Sqrt[(pi)^2(5/4)]
==> T = (Pi/2)sqrt(5)
==> T = (3.14/2)(2.236)
==> T = 3.5

The time taken by the child to complete one cycle = 3.5 seconds.

Hi,
You are no less.This is just the formula substitution and simplification.

Good Luck!!!