Question 1170606
z=(x-mean)/sd
a. z is > (36-45)/15 or -0.6, prob. 0.7257
b. at most 60 minutes is z < 15/15 or 1, probability 0.8413.
c. between the two is -0.6 < z < 1, with probability 0.5671
d. z is 1.645 for the 95th percentile, so x-mean=24.675 and x=69.675 min.  More than that.
e. this is z > (50-45)/15/sqrt(25) or z>1.6  with probability 0.0548
f. this is z > 5/15/sqrt(36) or z>2 with probability 0.0228