A cricketer has a certain average for 9 innings, In the tenth inning he scores 100 runs there by increasing his average by 8 runs. His new average is

28 runs

Let the old average of the cricketer be x.

According to the question:

\(\frac{\text{9x + 100} }{10 }\) = x + 8

9x + 100 = 10x + 80

x = 20

The old average of the cricketer comes out to be 20. Thus, the new average = x + 8 = 20 + 8 = 28 runs.