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Which of the following assertions are correct? P: Adding 7 to each entry in a list adds 7 to the mean of the list. Q: Adding 7 to each entry in a list adds 7 to the standard deviation of the list. R: Doubling each entry in a list doubles the mean of the list. S: Doubling each entry in a list leaves the standard deviation unchanged.
- P, Q
- Q, R
- P, R
- R, S
Correct answer: P, R
Solution
Adding the same constant to every value increases the mean by that constant but does not change the standard deviation. Doubling every value doubles the mean and also doubles the standard deviation, so only P and R are correct.
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