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Eighteen observations have mean 7 and standard deviation 4. The observation 12 is then deleted. Find the standard deviation of the remaining 17.

Competition practiceStatistics

A3.81
B4.12
C3.92
D4

Step-by-Step Solution

Sum

= 126 \to 114

, new mean

\approx 6.706.Σ x^{2} = 18 (16 + 49) = 1170 \to 1170 - 144 = 1026

. Variance

= \frac{1026}{17} - 6.70 6^{2} \approx 15.38

, SD

\approx 3.92

.

Answer: C) 3.92

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