Question

The average of the two numbers is 21. If any third number is added , then the average drops to 90​

Answer 1

The average of the two numbers is 21. If any third number is added , then the average drops to 90​, the third number is 228.

To find the third number.

Average of two numbers = 21

So, the sum of the two numbers = 2×21 = 42

When, the third number is added, average becomes = 90

So, the sum of the 3 numbers = 3×90 = 270

Thus, the third number is equal to:

Sum of 3 numbers - Sum of 2 numbers

= 270 - 42

= 228