Here the xi are of large numerical values.
So we use deviation method then,
\(\overline{x}= a+\frac{\Sigma f_id_i}{\Sigma f_i}\)
Here the assumed mean is taken as 275.
∴ \(\overline{x}= a+\frac{\Sigma f_id_i}{\Sigma f_i}\)
= 275 + \(\frac{1900}{50}\)
= 275 + 38
= 313.