The average of 9 numbers is 3. If the average of the first 8 of these numbers is 2, the 9th number is:
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e 11.
Average of 9 numbers = 3
So, total of 9 numbers = 3 × 9 = 27
Average of first 8 numbers = 2
So, total of first 8 numbers = 2 × 8 = 16
9th number = Total of 9 numbers – Total of first 8 numbers
9th number = 27 − 16 = 11