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Eight observations have mean 12. When a 9th observation is included, the mean drops to 11.
Find the value of the 9th observation.

Class 9Measures of Central TendencyStatistics and Probability

A3
B4
C6
D2

Step-by-Step Solution

Total of

8 = 8 \times 12 = 96

. Total of

9 = 9 \times 11 = 99

. 9th observation = 99 - 96 = 3.

Answer: A) 3

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