A random variable X has a mean of 120 and a standard deviation of 15 a random variable Y has a mean of 100 and a standard deviation of 9. If X and Y are independent approximately what is the standard deviation of X plus Y.

A random variable X has a mean of 120 and a standard deviation of 15 a

1.	A random variable X has a mean of 120 and a standard deviation of 15 a random variable Y has a mean of 100 and a standard deviation of 9. If X and Y are independent approximately what is the standard deviation of X plus Y.
Answer» A random variable X has a mean of 120 and a standard deviation of 15 a random variable Y has a mean of 100 and a standard deviation of 9. If X and Y are independent approximately what is the standard deviation of X plus Y. Solution: