@Sushant Hajare
The mean period of oscillation will be
T=2.63+2.56+2.42+2.71+2.8/5
=2.62 sec
The errors in the measurement wil be
2.63-2.62=.01sec
2.56-2.62=-.06sec
2.42-2.62=-.2sec
2.71-2.62=.09sec
2.80-2.62=.18 sec
so mean of absolute error will be .11sec
Hence Period of oscillation will be (2.62±0.11)
Therefore T=2.6±.1s
relative error or percentage error is given by
=0.1/2.6*100
4%