- 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

_{}

_{}

_{}

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