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AP® Statistics

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Moderate

Mean and Standard Deviation Difference for Two Random Variables.

APSTAT-LZLLJD

Random variable A is normally distributed with a mean of 20 and a standard deviation of 5. Random variable B is normally distributed with a mean of 35 and a standard deviati​on of 12. If A and B are independent variables which of the following describes the distribution of A $-$ B?

A

Normal with a mean of -15 and a standard deviation of -7

B

Normal with a mean of -15 and a standard deviation of 13

C

Normal with a mean of -15 and a standard deviation of 17

D

Normal with a mean of 15 and a standard deviation of -7

E

Normal with mean of 15 and a standard deviation of 17