A batsman in his 12th innings makes a score of 97 runs and thereby increases his average by 3 runs. What is his average (in runs) after the 12th innings?

The average of 100 numbers is 40. If one of the numbers, 30, is replaced by 70 while keeping the other numbers same, what is the new average?

The arithmetic mean of 22.5, 56, 42.5, 2x + 1, x - 2, 3x, and 36 is 30. Find the value of x (where x > 0).