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If out of 10 selected students for an examination, 3 were of 20 years, age, 4 of 21 and 3 of 22 years, the average age of the group is
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- 22 years
- 21 years
- 21.5 years
- 20 years
- 22 years
Correct Option: B
As per the given details in question ,
| Average age of the whole group = | 3 × 20 + 4 × 21 + 3× 22 |
| 10 |
| Average age of the whole group = | 60 + 84 + 66 |
| 10 |
| Average age of the whole group = | 210 |
| 10 |
Hence , Average age of the whole group = 21 years
