arithmetic - a batsman in his 13th innings makes a score of 77 and there by increases his average by 4 what is his average after the 13th innings - skillgun

Solution: Let the average of 12 innings be x. then, After 13th innings the average will become
12x + 77
=> ----------- = x + 4
13
By solving we will get x = 25.
Hence the average after 13th innings is x + 4 = 25 + 4
= 29.