A cricketer's average in his first 18 innings was 16.5 runs.
After a further 8 innings, his average had increased to 32.5 runs.
What was his average for the last 8 innings?
Note: you don't need any cricket skills to solve this puzzle, nor do you need to know what an innings consists of.
Answer: His average was 68.5 runs.
After the initial 18 innings, the average was 16.5, giving a total of 18 * 16.5 = 297 runs.
There were 26 innings in total, with an average of 32.5 runs.
Therefore an overall total of 26 * 32.5 = 845 runs.
Therefore 845 - 297 = 548 runs were run in the final 8 innings, giving an average of 548 / 8 = 68.5 runs.