1. Let x be a random variable that represents the length of time it takes a student to complete Dr. Tracy Wang’s homework. From long experience, it is known that x has a normal distribution with mean hours and standard deviation hour.

Convert each of the following x intervals to standard z intervals.

(a)

(b)

(c)

(d)

Solution: (a) We have that

(b) We proceed analogously to get

(c) Similarly

(d)

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