The average of some natural numbers is 15. If 30 is added to the first number and 5 is subtracted from the last number t…

The average age of 11 players of a cricket team is increased by 2 months when two of them aged 18 years and 20 years are…

Average age of 6 sons of a family is 8 years. Average age of sons together with their parents is 22 years. If the father…

In a class, there are 40 boys and their average age is 16 years. One boy, aged 17 years, leaving the class and another j…

If average of 20 observations x<sub>1</sub>, x<sub>2</sub>, . . . . . x<sub>20</sub>…

The average of 11 results is 50. If the average of the first six results is 49 and that of the last six is 52, the sixth…

The average of 25 results is 18. The average of first 12 of those is 14 and the average of last 12 is 17. What is the 13…

The average of the three numbers x, y and z is 45. x is greater than the average of y and z by 9. The average of y and z…