Answer each of the following parts (a) - (d) independently.

a. A normal distribution has a mean equal to 55. What is the standard deviation of this distribution if 10.56% of the area under the curve lies in the area to the left of X = 35?

b.A normal distribution has a standard deviation equal to 12. What is the mean if the

probability of scoring above X = 70 is 0.1587?

c.What z-score best represents P28?

d.What z-score best represents P89?