Section 11.3
1) What percent of the area under the curve lies to the right of the mean?
2) Suppose a score is chosen at random. What is the probability that it lies to the right of the
mean?
3) What percent of the area under the curve lies between µ - σ and µ + σ?
4) Suppose a score is chosen at random. What is the probability that it lies within one standard
deviation of the mean?
5) This example will help you do exercises 9-14, 19-22 on p.533
Z denotes the standard normal random variable. Find:
a) P(0 ≤ Z ≤ 1.95)
b) P( -2 ≤ Z ≤ 0)
c) P( Z ≤ .79)
d) P( Z ≥ 1.3)
e) P( 1.11 ≤ Z ≤ 2.49)
f) P( -.03 ≤ Z ≤ 1.98)
g) P( Z ≥ 5.9)
6) This example will help you do exercises 23-26 on p.534
Let X be a normal random variable with µ = 0.51 and σ = 0.23. Find:
a) P ( X ≤ .65)
b) P ( -.65 ≤ X ≤ -.15)
7) This example will help you do exercises 27-32, 34 on p.493
Suppose the annual rainfall in Statville is known to be normally distributed with a mean of 35.5
inches and a standard deviation of 2.5 inches. In a randomly selected year, what is the
probability that the rainfall exceeds 41 inches?
8) Without using the table, find:
P( Z < -3) + P(-3 ≤ Z ≤ -1) + P( -1< Z ≤ 2) + P( Z > 2)
Section 11.4
1) A fair coin is tossed 100 times. What is the probability that we get:
a) between 40 and 60 heads, inclusive?
b) exactly 50 heads?
2) The admissions office at Slippery Rock University knows from past experience that 60% of
all high school applicants will enroll as freshmen. If 1200 high school students apply for
admissions for next year, what is the probability that no more than 750 will enroll?