1. RES 342 FINAL EXAMS
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1) What are the critical z-values for a two-tailed hypothesis test if the significant level = 0.01?
2) In classical hypothesis testing, the test statistic is to the critical value what the __________.
3) For a hypothesis test of a single population mean at 95% confidence level, a calculated Z score of 1.7
supports the conclusion that
4) If the paired differences are normal in a test of mean differences, then the distribution used for testing
is the
5) One hundred women were polled and 60 reported successfully communicating an automobile problem
to an auto repairman. A sample of 150 men had 95 reporting the same success. The value of the test
statistic for a test of the equality of proportions is
6) Weekly sales of iPods® at 20 Best Buy® stores are compared before and after installing a new eye-
catching display. To determine if the display is effective in increasing sales, what type of statistical test
would you perform?
7) When is it appropriate to use the paired difference t-test?
8) A survey of hotels found that the average hotel room rate in New Orleans is $88.42 and the average
room rate in Phoenix is $80.61. The survey sampled 50 hotels in each city. The standard deviations were
$5.62 and $4.83, respectively. At alpha=.05, it can be concluded that there is a significant different in the
rates?
9) If the paired differences are normal in a test of mean differences, the distribution used for testing is the
10) The accountant for Thomas’s Furniture Store is concerned regarding the outstanding receivable owed
the company. There has been a cash flow problem and it is believed that the slow collection of accounts
receivable is partially the blame. The accountant believes that 40% of the present accounts are more than
4 months behind in making payments. To be able to make a decision regarding this belief, a random
sample of 100 accounts was taken. It was found that 37 accounts were more than 4 months late. Did the
sample data confirm the accountant’s belief? Use the .05 significant level for the statistical test.
11) New college business graduates are finding it difficult to get a job. A business journal has reported
that only one in five graduates is able to find a job within 6 months of their graduation. A report by
University of Phoenix indicated that out of a survey of 300 recent business graduates, 75 had jobs. You
are a business major at University of Phoenix and have a concern about getting a job. Based on this data,
will a graduate of University of Phoenix have a better chance of getting a job in the first 6 months after
graduation? Use the .05 significant level for the test.
12) Analysis of variance (ANOVA) is used to
13) Mr. Thomas owns three different restaurants in Cincinnati, Ohio. He is concerned about the
profitability of the restaurants. There are monthly differences between the restaurants and he wants to
determine if the differences in profit are significant. Mr. Thomas wants to do a statistical test to see if he
should be concerned. The best test to address this problem would be
14) Sound engineers studied factors that might affect the output, in decibels, of a rock concert’s speaker
system. The desired level of significance was a = .05. The results of their ANOVA tests are shown:
Source of Variation SS df MS F P-value
Amplifier 99.02344 99.02344 0.005718
Position 93.98698 31.32899 3.215807 0.051003
2. Interaction 10.15365 3 3.384549 0.347412 0.791505
Error 155.875 16 9.742188
Total 359.0391 23
The interaction between the Position and Amplifier treatments was
15) Totto, an automobile manufacturer, has designed a radically new engine and wants to recommend the
grade of gasoline that will have the best fuel economy. The four grades are regular, below regular,
premium, and super premium. The test car made three trial runs on the test track using each of the grades
and the miles per gallon were recorded. At the 0.05 level, what is the critical value of F used to test the
hypothesis that the miles per gallon for each fuel are the same?
16) If an ANOVA test is conducted and the null hypothesis is rejected, what does this indicate?
17) Nonparametric statistics are used when
18) The nonparametric test most commonly used for testing the statistical independence between two
variables is
19) What nonparametric test is used when the assumptions for the parametric ANOVA cannot be met? Its
purpose is to test whether three or more populations are equal. The data must be at least ordinal scaled.
20) Rachael Smith is the personnel manager at Johnson and Johnston, an accounting firm. She is
concerned about absenteeism, which seems to be an increasing problem, especially after days off work.
She decided to sample the records to determine if absenteeism was distributed evenly throughout the 6-
day work week. The null hypothesis to be tested was: Absenteeism is distributed evenly throughout the
week. The sample results were:
Day of Week Number Absent
Monday 12
Tuesday 9
Wednesday 11
Thursday 10
Friday 9
Saturday 9
What is the critical value of chi-square with a significant level of = 0.05?
21) A public opinion poll surveyed a simple random sample of voters. Respondents were classified by
gender and by voting preference—Republican, Democrat, or Independent. The results follow.
Voting Preferences Republican Democrat Independent Row total
Male 200 150 50 400
Female 250 300 50 600
Column total 450 450 100 1000
If you conduct a chi-square test of independence, what is the expected frequency count of male
Independents?
22) What parametric test is equivalent to the nonparametric Spearman's rank test?
23) What is the variable used to predict another variable called?
24) Michelle used a sample of 50 U.S. cities to estimate the relationship between crime, or annual
property crimes per 100,000 persons, and income, or median income per capita. Her estimated regression
equation was crime = 428 - .01 income. Assuming her model is statistically significant, if income
decreases by $1,000, we would predict that crime will
25) In the least squares equation, Y' = 12 + 25X the value of 25 indicates
26) A test is conducted in eight cities to see if giving away free transit system maps will increase bus
3. ridership. In a regression analysis, the dependent variable is the increase in bus ridership in thousands of
persons from the start of the test until its conclusion. The independent variables are X1 = the number in
thousands of free maps distributed and X2 = a binary equal to 1, if the city has free downtown parking
and 0 otherwise. The estimated regression equation is Y = 1.32+.0345X1-1.45X2. If the Y value for city 3
is 7.3, X1 = 140, and X2 = 0 the residual for city 3 in thousands is:
27) The following linear trend equation was developed for the annual sales of the Tractor Manufacturing
Company. Y' = 355 + 50t in thousands of dollars. How much are sales increasing by? 28) The time series
component that reflects variability over short, repetitive time periods that last less than one year is called
29) A research company has been hired by a realty company to do an analysis of heating cost of homes in
the region. The realty company wanted to be able to predict the heating cost of a typical single-family
home. The realty company was constantly being asked questions regarding heating costs by potential
home buyers. It was believed that these variables would impact heating costs (Y'): mean daily outdoor
temperature (X1), the number of inches of insulation (X2), and the age in years of the furnace (X3). The
multiple regression analysis produced the following regression equation: Y' = 427.2 – 4.58X1 – 14.83X2
+ 6.10X3. Which statement is correct based on this analysis?
30) If we fit a linear trend to data that are growing exponentially,
