STAT 201 - Quiz 4 - Fall 2022
Section:
Name:
1.
20 points
The following contingency table cross classifies where students live by their classification for the
3,119 students at a small private university.
Living
Status
On-campus
Off-campus
Column Totals
Freshman
550
210
760
Classification
Sophomore
Junior
426
378
308
425
734
803
Senior
275
547
822
Row
Totals
1629
1490
3119
(a) (3 points) What is the probability that a randomly selected student is a junior?
(b) (3 points) What is the probability that a randomly selected student lives on-campus and is a
freshman?
(c) (3 points) What is the probability that a randomly selected student lives off-campus or is a
senior?
(d) (3 points) If a student is a sophomore, what is the probability that they live on-campus?
(e) (2 points) Which classification (Freshman, Sophomore, Junior, Senior) is most likely to live
on-campus? Explain your answer.
2
2. (3 points)
For a population of students, suppose we are interested in the event that a student
is left-handed and the event that a student wears glasses. Which of the following is most likely?
(a). The event that a student is left-handed and wears glasses.
(b). The event that a student wears glasses.
(c). The event that a student is left-handed.
(d). The event that a student is left-handed or wears glasses.
3. (3 points)
Ember, a German shepherd, is expected to have a litter of three puppies and we are
interested in the potential sexes of the puppies. Since she is having three puppies, a potential outcome
for the litter would be M F M which implies that the first puppy was a male, the second puppy was
a female, and the third puppy was a male. Using this pattern, the sample space for the different
possible sexes of the three puppies is as follows:
S = {M M M, M M F, M F M, M F F, F M M, F M F, F F M, F F F }
Let’s consider the events A = {at least two puppies are female} and B = {at least two puppies are male}.
If all outcomes in the sample space are equally likely, which of the following statements is true?
(a). Event A is more likely than event B.
(b). Events A and B are equally likely.
(c). Event A is less likely than event B.
(d). Since the puppies have not yet been born, we cannot make any declaration about the likelihood
of A or B.