- 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)
