`g=4pi^(2)L//T^(2)`
Here, `T=t/n` and `Delta T=(Delta t)/n`. Therefore, `(Delta T)/T=(Delta t)/t`.
The errors in both L and t are the least count errors. Therefore,
`(Delta g//g)=(Delta L//L)+2(Delta T//T)`
`=0.1/20.0+2(1/90)=0.027`
thus, the percentage error in g is
`100(Delta g//g)=100 (Delta L//L)+2xx100 (Delta T//T)`
`=3 %`