A) 12
B) 10
C) 9
D) 8
Correct Answer: C
Solution :
Given that, Mean of 7 observations = 7 \[\Rightarrow \] \[\frac{1}{7}\sum\limits_{i=1}^{7}{{{x}_{i}}=7}\] \[\Rightarrow \] \[\sum\limits_{i=1}^{7}{{{x}_{i}}=49}\] ?(i) If each observation is increased by 2. then, new mean \[=\frac{1}{7}\sum\limits_{i=1}^{7}{({{x}_{i}}+2)}\] \[=\frac{1}{7}\left\{ \sum\limits_{i=1}^{7}{{{x}_{i}}+2\times 7} \right\}\] \[=\frac{1}{7}\{49+14\}=\frac{1}{7}\times 63=9\]
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