Question

The average of four numbers is 98. If three of the numbers are 86,87,and 91 what is the fourth number?

Answer 1

To find the average, you have to add all the numbers up and then divide by the amount of numbers you added together.

Equation: (86+87+91+x)/4=98
Solve for x:
86+87+91+x=98*4
264+x=392
x=392-264
x=128

The fourth number is 128