The average of 12 numbers is 28. If one number, 42, is replaced by another number, the average decreases by 1.5. What is the number that replaces 42?

The average of four numbers is 12.5. If each number is increased by 2.5, then the new average will be:

The arithmetic mean of the numbers 9, 12, 15, 18, 20, 22 is increased by 1, if 15 is replaced by

If the average of m numbers is n*n and that of n numbers is m*m , then the average of m+n numbers is

The average of 6 numbers is 5. The first number is increased by 2, second by 4, third by 8 and so on. The average of new numbers is

The average of the first 8 numbers is 42. The average of the first 4 numbers is 40, and the average of the next 3 numbers is 44. What is the 8th number?