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The standard deviation of a set containing 25 values is 40. If 5 is added to each value in the set, what will the updated standard deviation be?

1. 40
2. 45
3. 40 + 21/25
4. 40 − 21/25

Correct answer: 40

Solution

The updated standard deviation remains 40 because adding a constant to each value in the set does not change the spread of the data, and thus the standard deviation remains the same.

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