A simple pendulum makes 115 complete oscillations in 240 min

A simple pendulum makes 115 complete oscillations in 2.40 min at a location where g = 9.80 m/s^2. Find the period of the pendulum. Find the length of the pendulum.

Solution

time period = time taken in one oscillation

=> T = 2.4*60)/(115 =   1.25 sec

b)

T = 2pi*sqrt(L/g)

=> L = (1.25/(2*3.14))^2*9.8 = 0.388 m