Question: Shaun (3 years old) and Patrick (4 years old) are each allowed to pick one book for bedtime stories, and the parent on duty reads the two books sequentially. The times for reading (single) books in the collection from which they select are approximately normally distributed, with a mean of 5 minutes and a standard deviation of 2 minutes.
a. Does it make sense to assume that the times for the two books are independent? Explain.
b. On about what proportion of nights will story time exceed 15 minutes, assuming that the times for the two books are independent?