There are 1600 students in a college, whose average weight is 50 kg. If average weight of boys is 54 kg. and average weight of girls is 38 kg. Then find the number of girls in the school.

The average weight of 8 people increase by 2.5 kg when a new person comes in place of one of them weighting 75 kg. What is the weight of the new person?

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

The average of a,b,c is 20 and that of b,c,d is 25, if d=30, then the value of a is-

Among three numbers, the first is twice the second and thrice the third. If the average of the three numbers is 49.5, then the difference between the first and the third number is: 

What is the average of the first five prime numbers?

The average salary of 12 employees in a company was recorded to be ₹20,000. If the salary of the manager is also included, then the average salary increases by ₹2,000. Find the salary of the manager.

The average of 8 readings is 24.3, out of which the average of the first two is 18.5 and that of next three is 21.2. If the sixth reading is 3 less than seventh and 8 less than eight, what is the sixth reading?