The average of nine numbers is 7. If the average of six of the numbers is 8, then the average of the remaining numbers is:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 5
An average times the number of values gives their sum, so the sum of the remaining numbers is the total sum less the sum of the six.
Sum of all nine numbers \(=9\times7=63\)
Sum of the six numbers \(=6\times8=48\)
Sum of the remaining three \(=63-48=15\)
Their average \(\displaystyle =\frac{15}{3}=5\)