1. The problem statement, all variables and given/known data A person shakes pendulum with length 3.6 meters. For 12 shakes he measured the time of 38 seconds. Find the acceleration due to gravity 2. Relevant equations T=t/n T=2*pi*sqrt(l/g) 3. The attempt at a solution T(period)=t/n=3.167 T=2*pi*sqrt(l/g) l-length g=4*(pi)^2*l/T^2 g=14.156 The solution in my book is 9.4 m/s^2. Where is my error?