1. (TCO 9) The hours of study and the final
exam grades have this type of relationship:
ลท = 6.75(hours) + 37.45. Based on this linear
regression equation, estimate the expected grade for a student spending 8 hours
studying. Round your answer to two decimal places. (Points : 6)
91.45
54
93.42
89.45
2. (TCO 5) Historical sales records show that
40% of all customers who enter a discount department store make a purchase. We
are interested in calculating the probability that 3 of 5 customers make
purchase. Choose the best answer of the following: (Points : 6)
This is an example of a Poisson probability
experiment
This is an example of a Binomial probability
experiment
This is neither a Poisson nor a Binomial
probability experiment
Not enough information to determine the type of
experiment
3. (TCO 5) Microfracture knee surgery has a 75%
chance of success on patients with degenerative knees. The surgery is performed
on 5 patients. Find the probability of the surgery being successful on less
than 3 patients?(Points : 6)
0.103516
0.632813
0.263672
0.087891
4. (TCO 5) It has been recorded that 10 people
get killed by shark attack every year. What is the probability of having 3 or 4
people get killed by shark attack this year? (Points : 6)
0.026484
0.029253
0.018917
0.010336
5. (TCO 2) The mean teaching hours for a full
time faculty at a state university is eight hours per week. What does this tell
you about the typical teaching hours for full time faculty at that university?
(Points : 6)
Half the full time faculties teach less than
eight hours per week while half teaches more than eight hours per week.
The average teaching hours for full time
faculty is eight hours per week.
More full time faculty teaches eight hours per
week than any other number of teaching hours.
The number of teaching hours for full time
faculty in not very consistent because eight is such a low number.
6. (TCO
6) Assuming that the data are normally distributed with a mean of 25 and a
standard deviation of 1.25, what is the z-score for a value of 27? (Points : 6)
2.30
1.60
3.10
-1.60
7. (TCO 8) The mean hours of Internet usage by
adults in the US in claimed to be 25 hours per week. A hypothesis test is
performed at a level of significance of 0.05 with a P-value of 0.01. Choose the
best interpretation of the hypothesis test. (Points : 6)
Reject the null hypothesis; there is enough
evidence to reject the claim that the mean of hours Internet usage by adults in
the US is 25 hours per week.
Reject the null hypothesis; there is enough
evidence to support the claim that the mean hours Internet usage by adults in
the US is 25 hours per week.
Fail to reject the null hypothesis; there is
not enough evidence to reject the claim that the mean hours of Internet usage
by adults in the US is 25 hours per week.
Fail to reject the null hypothesis; there is
not enough evidence to support the claim that the mean hours of Internet usage
by adults in the US is 25 hours per week..
8. (TCO 8) A result of an entry level exam
reveals that 22% of students fail that exam.
In a hypothesis test conducted at a level of
significance of 2%, a P-value of 0.0128 was obtained. Choose the best
interpretation of the hypothesis test. (Points : 6)
Fail to reject the null hypothesis; there is
not enough evidence to reject the claim that 22% of students fail the entry
level exam.
Fail to reject the null hypothesis; there is
not enough evidence to support the claim that 22% of students fail the entry
level exam.
Reject the null hypothesis; there is enough
evidence to reject the claim that 22% of students fail the entry level exam.
Reject the null hypothesis; there is enough
evidence to support the claim that 22% of students fail the entry level exam.
9. (TCO 2) A bank is going to choose between
two systems A and B which helps in measuring customers waiting time. During the
trial period, both systems showed an average waiting time of 10 minutes. Type A
showed a standard deviation of 2 minutes while type B showed a standard
deviation of 4 minutes. Which of the two systems the bank should choose?
(Points : 6)
System A because in shows more consistency in
measuring the average waiting time.
System B because in shows more consistency in
measuring the average waiting time.
Either because their mean waiting time is the
same in both systems.
Neither because the given information is not
enough to make a decision
10. (TCO 4) A jar contains balls of four
different colors; red, blue, yellow and green. The total balls are divides as
45% red, 35% blue, 15% yellow, and 5% green. If you are to select one ball at
random. Find the expected value of your winning amount if the payments are set
to be $5, $15, $25, $60 for red, blue, yellow and green ball respectively.
Winning amount
5
15
25
60
Probability
45%
35%
15%
5%
The expected winning amount is $28.50
The expected winning amount is $14.25
The expected winning amount is $25.50
The expected winning amount is $11.25
11. (TCO 3) The grades of 22 students are
listed below. Use the stem & leaf to determine the shape of the
distribution. Choose the best answer.
4 | 7 5
5 | 1 7 5
6 | 5 6 7 8 9
7 | 1 6 7 8 8 9
8 | 2 4 7 6
9 | 4 7
(Points
: 6)
The data is symmetric
The data is skewed to the right
The data is skewed to the left
The data is bimodal
12. (TCO 1) A researcher is interested in
studying people’s mean age in a certain region. If the population standard
deviation is known to be 8 years and 1.5 year of error margin is allowed, find
the minimum simple size the researcher needs to use, knowing that he is going
to conduct his study using 95% confidence level. (Points : 6)
Sample Size = 77
Sample Size = 25
Sample Size = 210
Sample Size = 110
13. (TCO 6) Horse race time is found to be
normally distributed with a mean value of 18 minutes and a standard deviation
of 4 minutes. Horses whose race time is in the top 6% will not be eligible to
participate in a second round. What is the lowers race time that makes a horse
losses his eligibility to participate in a second round? (Points : 6)
26.6
11.8
24.2
20.3
14. (TCO 5) A class containing 25 students 12
of them are females. In how many ways can we select a group of 6 male students?
(Points : 6)
1716
665280
1235520
924
15. (TCO 6) Research shows that the life time
of Everlast automobile tires is normally distributed with a mean value of
60,000 miles and a standard deviation of 5,000 miles. What is the probability
of having a tire that lasts more than 67,000 miles? (Points : 6)
0.9192
0.0808
1.40
0.0793
16. (TCO 10) A research shows that employee
salaries at company XYX, in thousands of dollars, are given by the equation
y-hat= 48.5 + 2.2 a + 1.5 b where ‘a’ is the years of experience, and ‘b’ is
the education level in years. In thousands of dollars, predict the salary for
an employee with 5 years experience and 16 years education level. (Points : 6)
52.5
59.5
83.5
69.5
17. (TCO 9) The estimated value for the
correlation coefficient for this graph might be
(Points
: 6)
-0.91
0.50
0.91
-0.50
1.
(TCO
8) For the following statement, write the null hypothesis and the alternative
hypothesis. Also label which one is the claim.
2. (TCO 11) A pizza restaurant
manager claims that the average home delivery time for their pizza is no more
than 20 minutes. A random sample of 49 home delivery pizzas was collected. The
sample mean was found to be 21.25 minutes and the standard deviation was found
to be 4.3 minutes. Is there evidence to reject the manager’s claim at alpha
=.01? Perform an appropriate hypothesis test, showing the necessary
calculations and/or explaining the process used to obtain the results. (Points
: 20)
3. (TCO 5) A researcher found that
85% of customers who make purchase at a department store are pleased with the
store customer service. We asked 20 customers whether or not they are please
with the store customer service.
(a) Is this a binomial experiment? Explain how
you know.
(b) Use the correct formula to find
the probability that, out of 20 customers, exactly 12 of them are pleased with
the store customer service. Show your calculations or explain how you found the
probability. (Points : 20)
4. (TCO 6) The monthly utility bills
are normally distributed with a mean value of $150 and a standard deviation of
$20.
(a) Find the probability of having a
utility bill between 135 and 170.
(b) Find the probability of having a
utility bill less than $135.
(c) Find the probability of having a
utility bill more than $180. (Points : 20)
5. (TCO 8) A Mall manager claims
that in average every customer spends $37 per a single visit to the mall. To
test this claim, you took a sample of 64 customers and found the sample mean to
be $34 and the sample standard deviation to be $5. At alpha = 0.05, test the
Mall’s manager claim. Perform an appropriate hypothesis test, showing the
necessary calculations and/or explaining the process used to obtain the
results. (Points : 20)
6. (TCO 7) A bank manager wanted to
estimate the mean number of transactions businesses make per month. For a
sample of 50 businesses, he found the mean number of transaction per month to
be 35 and the standard deviation to be 9.5 transactions.
(a) Find a 99% confidence interval
for the mean number of business transactions per month. Show your calculations
and/or explain the process used to obtain the interval.
(b) Interpret this confidence
interval and write a sentence that explains it. (Points : 20)
7. (TCO 7) A company’s CEO wanted to
estimate the percentage of defective product per shipment. In a sample
containing 400 products, he found 25 defective products.
(a) Find a 95% confidence interval
for the true proportion of defective product. Show your calculations and/or explain
the process used to obtain the interval.
(b) Interpret this confidence
interval and write a sentence that explains it. (Points : 20)
8. (TCO 2) The ages of 10 students
are listed in years:{ 17,20,18,24,21,26,29,18,22,28}
(a) Find the mean, median, mode, sample
variance, and range.
(b) Do you think that this sample
might have come from a normal population? Why or why not? (Points : 20)
