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The average of 6 observations is 12. A new seventh observation is included and the new average is decreased by 1. Find the seventh observation.
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- 5
- 7
- 8
- 9
- 5
Correct Option: A
The average of 6 observations = 12
Sum total of 6 observations = 6 × 12
The average of 7 observations = 11
Sum of 7 observations = 7 × 11
Seventh observation = Sum of 7 observations – Sum total of 6 observations
∴ Seventh observation = (7 × 11) – (6 × 12) = 77 – 72 = 5
