A batsman in his 13th innings makes a score of 97 runs, thereby increasing his average score by 5.  What is his average score after his 13th innings?

37

Extra runs score by him to increase average only is:

13 Inning × 5 (+ Avg.) = 65

Remaining 97 – 65 = 32 runs score to maintain previous average

⸫ Previous average = 32

New average = 32 + 5 = 37