Question

The average marks secured by 15 students are 70 and later it was found that one entry is wrong and 65 is written instead of 45. Find out the corrected average.

Answer 1

$\Rightarrow$ Average marks of $15$ students are $70$.

$\Rightarrow$ Total marks of $15$ students $=15\times 70=1050$

$\Rightarrow$ It is given that one entry is wrong and $65$ is written instead of $45$

$\Rightarrow$ Then, correct total marks of $15$ students $=1050-65+45=1030$

$\therefore$ Correct average $=\frac{1030}{15}=68.66$