Average of 21 number is 36. If the average of first 12 numbers is 15, then find the average of remaining 9 number?

A certain sum is deposited for 4 years at a rate of 10% per annum on compound interest compounded annually. The difference between ihe interest at the end of 2 years and that at the end of 4 years is ₹5,082. Find the sum (in ₹).

The average salary per head of all the workers of JK Campus is ₹ 60. The average salary of 12 center heads is ₹ 400 and of the rest is ₹ 56. The total number of workers in JK Campus is 

The average of 5 numbers, arranged in a row, is 309. The average of the first two of these numbers is 431 and the average of the last two of these numbers is 231.5. What is the value of the number at the center of the row?

If (a + b): (b + c): (c + a) = 5: 6: 9 and a + b + c = 10. What is the value of c?

What is the average of all numbers between 100 and 200 which are divisible by 13?

A librarian purchased 60 story books for his library. But he found that he could get 4 extra books by spending Rs. 336 more and then the overall average price per book would be reduced by Re 1. The previous average price of each book was 

A batsman scores 98 run in the 17^th match of his career. His average runs per match increased by 2.5. What is his average before the 17^th match?