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The average of seven numbers is 18. If one of the number is 17 and if it is replaced by 31, then the average becomes :
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- 21.5
- 19.5
- 20
- 21
- 21.5
Correct Option: C
Given that , The average of seven numbers is 18.
If one of the number is 17 and if it is replaced by 31 , then
Difference = 31 – 17 = 14
| ∴ Required average = 18 + | = 20 | |
| 7 |
Second method to solve this question with the help of given formula :
Here, n = 7, m = 18 , a = 31, b = 17
| New Average = m + | |
| n |
| New Average = m + | |
| 7 |
| New Average = 18 + | |
| 7 |
New Average = 18 + 2 = 20
