Question

Ajit has a certain average for $9$ innings. In the tenth inning, he scores $100$ runs, thereby increasing his average by $8$ runs. What is his new average?

• A. $20$
• B. $21$
• C. $28$
• D. $32$

Answer 1

The correct option is C $28$

Let Ajit's average be $x$ runs for $9$ innings.
Then, Ajit scored $9x$ runs in $9$ innings.
In the ${10}^{\text{th}}$ inning, he scored $100$ runs.
Then average became $(x+8)$ and he scored $\left(\right(x+8)\times 10)$ runs in $10$ innings.
Now, $9x+100=10\times (x+8)$
$\Rightarrow 9x+100=10x+80$
$\Rightarrow x=20$
$\therefore$ New average $=(x+8)=28$ runs