Average Questions

The average of 21 numbers is 12. The average of the first 11 numbers is 9 and the average of the last 11 numbers is 15. What is the value of the middle number?

What is the average of all numbers between 8 and 74 which are divisible by 7?

Among three numbers, the first is twice the second and thrice the third. If the average of three numbers is 396, then what is the difference between the first and the third number?

The mean of 14 observations is 11. One more observation is included and the new mean becomes 12. The 15th observation is

The median of the numbers 14, 12, 12, 16, 13 and 18 is

Find the mean value of 2, 3, 3, 4, 6, 7

The mean of marks secured by 45 students in division A of class X is 69, 65 students of division B is 65 and that of 50 students of division C is 63. Find the mean of marks of the students of three divisions of Class X.

There are a total of 200 students in a school, of which 7/10th are boys. Find the number of girls in the school.