2025 MATH 221 STATISTICS EVALUATION QUESTIONS
WITH ANSWERS GRADED A+ 2025/2026
Fifty-four percent of US teens have heard of a fax machine. You randomly select 12 US
teens. Find the probability that the number of these selected teens that have heard of a
fax machine is exactly six (first answer listed below). Find the probability that the
number is more than 8 (second answer listed below).
0.284, 0.160
0.284, 0.120
0.217, 0.280
0.217, 0.120 - 0.217, 0.120
The probability of someone ordering the daily special is 71%. If the restaurant expected
65 people for lunch, how many would you expect to order the daily special?
46
51
35
34 - 46
(CO 3) Fifty-seven percent of employees make judgments about their co-workers based
on the cleanliness of their desk. You randomly select 8 employees and ask them if they
judge co-workers based on this criterion. The random variable is the number of
employees who judge their co-workers by cleanliness. Which outcomes of this binomial
distribution would be considered unusual?
1, 2, 8
1, 2, 8
0, 1, 8
0, 1, 2, 8 - 0, 1, 8
Seventy-nine percent of products come off the line ready to ship to distributors. Your
quality control department selects 12 products randomly from the line each hour.
Looking at the binomial distribution, if fewer than how many are within specifications
would require that the production line be shut down (unusual) and repaired?
Fewer than 7
Fewer than 6
Fewer than 9
Fewer than 10 - Fewer than 7
Out of each 100 products, 93 are ready for purchase by customers. If you selected 20
products, what would be the expected (mean) number that would be ready for purchase
by customers?
18
19
20
93 - 19
, Sixty-seven percent of adults have looked at their credit score in the past six months. If
you select 31 customers, what is the probability that at least 25 of them have looked at
their score in the past six months?
0.043
0.970
0.073
0.030 - 0.073
One out of every 92 tax returns that a tax auditor examines requires an audit. If 50
returns are selected at random, what is the probability that less than 5 will need an
audit?
0.0002
0.9999
0.9998
0.0109 - 0.9998
Thirty-eight percent of consumers prefer to purchase electronics online. You randomly
select 16 consumers. Find the probability that the number who prefer to purchase
electronics online is at most 3.
0.912
0.027
0.088
0.380 - 0.088
In the morning, about 28% of adults know what they will have for dinner. If one morning,
you ask 22 adults if they know what they will have for dinner, what is the probability that
more than 6 will say yes?
0.423
0.188
0.390
0.610 - 0.423
(CO 3) Among teenagers, 73% prefer watching shows over the internet, rather than
through cable. If you asked 104 teenagers if they preferred watching shows over the
internet, rather than through cable, how many would you expect to say yes?
73
104
75
76 - 76
Sixty-four percent of those that use drive through services believe that the employees
are at least somewhat rude. If you asked 87 people who use drive through services if
they believe that the employees are at least somewhat rude, what is the probability that
at most 50 say yes?
0.015
0.039
WITH ANSWERS GRADED A+ 2025/2026
Fifty-four percent of US teens have heard of a fax machine. You randomly select 12 US
teens. Find the probability that the number of these selected teens that have heard of a
fax machine is exactly six (first answer listed below). Find the probability that the
number is more than 8 (second answer listed below).
0.284, 0.160
0.284, 0.120
0.217, 0.280
0.217, 0.120 - 0.217, 0.120
The probability of someone ordering the daily special is 71%. If the restaurant expected
65 people for lunch, how many would you expect to order the daily special?
46
51
35
34 - 46
(CO 3) Fifty-seven percent of employees make judgments about their co-workers based
on the cleanliness of their desk. You randomly select 8 employees and ask them if they
judge co-workers based on this criterion. The random variable is the number of
employees who judge their co-workers by cleanliness. Which outcomes of this binomial
distribution would be considered unusual?
1, 2, 8
1, 2, 8
0, 1, 8
0, 1, 2, 8 - 0, 1, 8
Seventy-nine percent of products come off the line ready to ship to distributors. Your
quality control department selects 12 products randomly from the line each hour.
Looking at the binomial distribution, if fewer than how many are within specifications
would require that the production line be shut down (unusual) and repaired?
Fewer than 7
Fewer than 6
Fewer than 9
Fewer than 10 - Fewer than 7
Out of each 100 products, 93 are ready for purchase by customers. If you selected 20
products, what would be the expected (mean) number that would be ready for purchase
by customers?
18
19
20
93 - 19
, Sixty-seven percent of adults have looked at their credit score in the past six months. If
you select 31 customers, what is the probability that at least 25 of them have looked at
their score in the past six months?
0.043
0.970
0.073
0.030 - 0.073
One out of every 92 tax returns that a tax auditor examines requires an audit. If 50
returns are selected at random, what is the probability that less than 5 will need an
audit?
0.0002
0.9999
0.9998
0.0109 - 0.9998
Thirty-eight percent of consumers prefer to purchase electronics online. You randomly
select 16 consumers. Find the probability that the number who prefer to purchase
electronics online is at most 3.
0.912
0.027
0.088
0.380 - 0.088
In the morning, about 28% of adults know what they will have for dinner. If one morning,
you ask 22 adults if they know what they will have for dinner, what is the probability that
more than 6 will say yes?
0.423
0.188
0.390
0.610 - 0.423
(CO 3) Among teenagers, 73% prefer watching shows over the internet, rather than
through cable. If you asked 104 teenagers if they preferred watching shows over the
internet, rather than through cable, how many would you expect to say yes?
73
104
75
76 - 76
Sixty-four percent of those that use drive through services believe that the employees
are at least somewhat rude. If you asked 87 people who use drive through services if
they believe that the employees are at least somewhat rude, what is the probability that
at most 50 say yes?
0.015
0.039
