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1) The distribution of SAT Math scores of students taking
Calculus I at UTSA is skewed left with a mean of 625 and a
standard deviation of 44.5. If random samples of 100 students
are repeatedly taken, which statement best describes the
sampling distribution of sample means?
A) Shape is normal with a mean of 625 and standard deviation of 44.5.
B) Shape is normal with a mean of 625 and standard deviation of 4.45.
C) Shape unknown with a mean of 625 and standard deviation of 44.5.
D) Shape unknown with a mean of 625 and standard deviation of 4.45.
E) No conclusion can be drawn since the population is not normally
distributed.
2) A population has a normal distribution with a mean
of 50 and a standard deviation of 10. If a random
sample of size 9 is taken from the population, then
what is the probability that this sample mean will be
between 48 and 54?
A)0.000
D) 0.399
B) 0.228
E) 0.611
C) 0.385
3) Owners of a day-care chain wish to determine the proportion of
families in need of day care for the town of Helotes. The owners of
the day-care chain randomly sample 50 Helotes families and find only
4% of the returned questionnaires indicate these families having a
need for child day-care services. The 4% is best described as
A) the sample proportion of families in Helotes needing child day-care
services.
B) the sample proportion of families in Helotes with children needing
day-care services.
C) the population proportion of families in Helotes with children needing
day-care services.
D) the 30 families in Helotes needing day-care services for their
children.
E) the 600 families in Helotes with children needing day-care services.
A coach in a large high school thinks that ballet training will
improve the batting performance of his baseball team. He
decides to have a randomly selected half of the team take
six weeks of ballet training before the baseball season
begins while the other half does not take such training. He
will then compare the season batting averages of group A
(those with ballet training) and group B (those without ballet
training) by comparing the mean of group A with the mean
of group B.
4) This study would be classified as:
a. a survey
b. an observational study
c. an experimental study
A coach in a large high school thinks that ballet training will
improve the batting performance of his baseball team. He
decides to have a randomly selected half of the team take
six weeks of ballet training before the baseball season
begins while the other half does not take such training. He
will then compare the season batting averages of group A
(those with ballet training) and group B (those without ballet
training) by comparing the mean of group A with the mean
of group B.
5) The response variable is:
a. ballet training
b. batting average
c. runs batted in
d. the size of the school
e. the grades the players make in the ballet school
6)If P(A) = 0.24 and P(B) = 0.52 and events A and
B are independent, what is P(A or B)?
a)0.1248
c) 0.6352
b) 0.2800
d) 0.7600
e) The answer cannot be determined from the
information given.
7) Before premiering a blockbuster movie at a theater, test
screenings are done beforehand. A small number of
selected theaters are chosen geographically throughout the
country. Each theater chosen is supposed to be
representative of theatergoers in that area. Everyone is
interviewed when the movie is over. Identify the type of
sampling used in this example.
A)Stratified sampling
B) SRS
C) Cluster Sampling
D) Systematic Sampling
E) Convenience Sampling
8) A test consists of 10 true/false questions. If a
student guesses on each question, what is the
probability that the student will answer at least 9
questions correctly?
A)0.9
B) 0.001
D) 0.999
E) 0.011
C) 0.010
9) A basketball player has made 66% of his foul
shots during the season. Assuming the shots are
independent, find the probability that in tonight's
game he misses for the first time on his attempt?
A) 0.0426
B) 0.0281
D) 0.0827
E) 0.34
C) 0.1252
At George Washington High School students are heavily involved in extracurricular activities. Suppose that a student is selected at random from the
students at this school. Let the events A, M, and S be defined as follows,
with probabilities listed:
A = student is active in the performing arts:
M = student is active in vocal or instrumental music:
S = student is active in sports:
P(A) = 0.20
P(M) = 0.32
P(S) = 0.35
P( A Ç M ) = 0.18; P( A Ç S ) = 0.07; P( M | S ) = 0.30
Calculate the following (show your work): P( M Ç S )
P( M  S )
P( M | S ) 
P( S )
P( M  S )
0.30 
0.35
0.105  P( M  S )
2ND Nine weeks Review – Ch 11-18
1)B
2) E
3) A
4) C
5) B
6) C
7) C
8) E
9) A