Question

The average of P numbers is x, and the average of N numbers is y. What is the average of all the (P+N) numbers?

Answer 1

The sum of the P numbers is P * x
The sum of the N numbers is N * y
The total sum is (P * x) + (N * y) ...............(1)
The total quantity of numbers is (P + N) ............(2)
The average of all the (P + N) numbers is (1)/(2)