d The average of two numbers is XY.If one number is equal to X

# Word Problem 11:

Word Problem 11: The average of two numbers is XY.If one number is equal to X ,the other number is equal to_________?

a). X                        b). 2Y                                c). XY-X                         d). 2 XY – X

Solution:

We know the average of a given number of terms is calculated by dividing the sum of terms by their number.

There are two numbers and one number is given as X

We suppose the other number is Y

then the average of these 2 numbers is

$Average=\frac{x+y}{2}$

But average is given to be ‘xy’

So we get;

$xy=\frac{x+y}{2}$

from there we get;

$y=2xy-x$

so the option   d is correct