A random variable is normally distributed with a mean of 35 and a standard deviation of 5. If an observation is randomly selected from the distribution,

a. What value will be exceeded 10% of the time?

b. What value will be exceeded 80% of the time?

c. Determine two values of which the smaller has 5% of the values below it and the larger has 5% of the values above it. 

d. What value will 20% of the observations be below?