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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 $17$