Posted by **Rob** on Tuesday, November 15, 2011 at 12:00am.

Random variables X and Y are both normally distributed with mean 100 and standard

deviation 4. It is known that random variable X+Y is also a normal distribution.

a. What is the mean of X+Y?

b. What is the standard deviation of X+Y?

I see that the mean is 200 but I don't know how it arrived to.

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