Question

The mark obtained by $15$ students of a class test are $12,14,07,09,23,11,08,13,11,19,16,24,17,03,20$. Find
(i) the mean of their marks.
(ii) the mean of their marks when the mark of each student are increased by $4$.

Answer 1

The obtained marks by $15$ students arranging in ascending order,

$03,07,08,09,11,11,12,13,14,16,17,19,20,23,24$

$\left(i\right)$ $Mean=\frac{03+07+08+09+11+11+12+13+14+16+17+19+20+23+24}{15}$

$=\frac{207}{15}$

$=13.8$

$\left(ii\right)$ The new marks after increasing each student mark by $4$ are,

$07,11,12,13,15,15,16,17,18,20,21,23,24,27,28$

$Mean=\frac{07+11+12+13+15+15+16+17+18+20+21+23+24+27+28}{15}$

$=\frac{267}{15}$

$=17.8$