Three students S_1, S_2 and S_3 perform an experiment for determining the acceleration due to gravity (g) using a simple pendulum. They use different…

Three students $\displaystyle \mathrm{S}_1, \mathrm{~S}_2$ and $\displaystyle \mathrm{S}_3$ perform an experiment for determining the acceleration due to gravity (g) using a simple pendulum. They use different lengths of pendulum and record time for different number of oscillations. The observations are as shown in the table.

Student No.	Length of Pendulum (cm)	No. of oscillations (n)	Total time for n oscillations	Time period (s)
$\displaystyle 1$	$\displaystyle 64.0$	$\displaystyle 8$	$\displaystyle 128.0$	$\displaystyle 16.0$
$\displaystyle 2$	$\displaystyle 64.0$	$\displaystyle 4$	$\displaystyle 64.0$	$\displaystyle 16.0$
$\displaystyle 3$	$\displaystyle 20.0$	$\displaystyle 4$	$\displaystyle 36.0$	$\displaystyle 9.0$

(Least count of length $\displaystyle =0.1 \mathrm{~cm}$ least count for time $\displaystyle =0.1 \mathrm{~s}$ ) If $\displaystyle \mathrm{E}_1, \mathrm{E}_2$ and $\displaystyle \mathrm{E}_3$ are the percentage errors in ' g ' for students $\displaystyle 1,2$ and $\displaystyle 3$ respectively, then the minimum percentage error is obtained by student no. \_\_\_\_.