Determine the mean and the standard deviation of the total transit time for a DVD. b) On average, the return time Y is greater than the delivery time X. Determine the mean and the standard deviation of how much return time Y exceeds the delivery time X.
to complete with Netflix, the owner of a local movie rental store decides to try spending DVDs through the mail. To plan for this endeavor, she sends DVDs to her friends to obtain delivery times when DVDs are mailed to customers and return times when DVDs are mailed back to the store.
Let the random variable X denote the delivery time when a DVD is mailed to a customer, and let the random variable Y denote the return time when a customer mails the DVD back to the store. The store owner found that the
a) Determine the mean and the standard deviation of the total transit time for a DVD.
b) On average, the return time Y is greater than the delivery time X. Determine the mean and the standard deviation of how much return time Y exceeds the delivery time X.
Answer:- Given , The random variable X denote the delivery time.
E(X) = 1.2 days and SD(X) = 0.6 days
And let the random variable Y denote the return time.
E(Y) = 2.6 days and SD(Y) = 0.8 days
Using formula,
E(A+B) = E(A) +E(B)
E(A - B) = E(A) - E(B)
Var(A +B) = Var(A) + Var(B)
Var(A-B) = Var(A) + Var(B)
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