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The variance of 10 observations is 16. If each observation is doubled, what is the standard deviation of the new data?

1. (A) 8
2. (B) 16
3. (C) 4
4. (D) 32

Correct answer: (A) 8

Solution

Original variance = 16, so original SD = 4. Doubling each observation multiplies the SD by 2 (since SD scales linearly with the data), giving new SD = 8.

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