Simple pendulum and acceleration due to gravity physics question?

Question

A simple pendulum with a length 1.50 m makes 81.6 oscillations in 180 s. What is the acceleration due to gravity at its location? (It is not located on Earth!)

Answer 1

T= 2pisqrt(L/g)

g= L/(T/2pi)^2

g=L(2pi/T)^2 T=180/81.6=2.21 sec

g=1.5(2 pi / 2.21)^2=12.17 m/s^2 (Definitely not Earth)

g'/g=12.17/9.81=1.24
So it is something that is 24% heavier. What could that be?