The arithmetic mean of the following data is .

23, 17,20,19,21

For what value of m will the system of equations 17x+my+102=0 and 23x+299y+138=0 have infinite number of solutions? 

Find the average of the cubes of the first five natural numbers. 

If the 8-digit number 888x53y4 is divisible by 72, then what is the value of (7x + 2y) for the maximum value of y?

If a 7-digit number 54p3987 is divisible by 11 , then p is equal to:

If the seven-digit number 52A6B7C is divisible by 33, and A, B, C are primes, then the maximum value of 2A + 3B + C is:

In a proportion, the 1^st , 2^nd and 4^th  terms are 51, 68 and 108, respectively. What is the 3^rd term?

The least number that should be added to 35460 so that the sum is exactly divisible by 3, 4, 5 and 7 is: