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The average of five numbers is 7. When three new numbers are included, the average of the eight numbers becomes 8.5. The average of the three new numbers is
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- 9
- 10.5
- 11
- 11.5
- 9
Correct Option: C
Given that , The average of five numbers = 7
Sum of five numbers = 5 × 7
When three new numbers are included, then
The average of 8 numbers = 8.5
Sum of 8 numbers = 8 × 8.5
Sum of the three new numbers = 8 × 8.5 – 5 × 7 = 68 – 35
Sum of the three new numbers = 33
∴ Required average = 33 ÷ 3 = 11
