A batsman makes a score of 87 runs in the 17th inning and thus increases his averages by 3. What is his average after 17th inning?
39
35
42
40.5
Explanation:
Let the average after 17 innings = $x$
Total runs scored in 17 innings = 17$x$
Average after 16 innings = $\left(x-3\right)$
Total runs scored in 16 innings = 16$\left(x-3\right)$
Total runs scored in 16 innings + 87 = Total runs scored in 17 innings
=> 16 $ \left(x-3 \right) + 87 = 17x$
=> 16x - 48 + 87 = 17$x$
=>$x$ = 39