Statistics

Must show work

1) state hypothesis and identify the claim

2) find critical value(s)

3) compute test value

4) make decision to reject or not reject null hypothesis

5) summarize results

 

Can use excel.

Exam4

1

Instructions:

– You may work on the exam either alone or with one other student from your section; if you
choose the latter option, you only need to turn in one exam (with both names on it).

– The exam is due IN CLASS ON MONDAY, DECEMBER 10, 2012.
– You must turn the exam in IN-PERSON, IN CLASS.
– USE SEPARATE SHEETS OF PAPER FOR YOUR WORK AND ANSWERS.
– I will deduct twenty (20) points from your grade for the exam for every hour that it is late
– Please retain a copy of your exam.
– SHOW YOUR WORK.
– IF YOU ARE USING EXCEL FOR ANY PORTION OF THE EXAM, PROVIDE

THE PRINTOUT TO RECEIVE FULL CREDIT.

– USE PROPER NOTATIONS.

**If you have any substantive questions, you must ask them in class
on either Wednesday, December 3, 2012 or via OnCourse no later

than 5:00 PM on Saturday, December 8, 2012. I will not respond to
any emails after that time.**

Question 1 (20 points)

A sample of 5 local mixed martial arts studios shows their profits (in thousands of dollars) 5 years
ago and their profits (in thousands of dollars) today. At α = 0.05, can it be concluded that the
average in profits for these studios is greater today than it was 5 years ago? Assume the variables are
normally distributed. Use the traditional method of hypothesis testing. HINT: make sure you think
hard about your alternative hypothesis.

Studio Profit 5 Years Ago Profit Today

Dragon 120 150

Monkey 100 95

Phoenix 200 260

Centaur 80 100

Liger 65 85

Extra Credit 1 (3 points)

Do Question 1 using the Data Analysis add-on in Excel. Provide a printout of your results.

Extra Credit 2 (2 points)

From your results in Extra Credit 1, if you were using the p-value method, what would your p-value

be?

K300 Spring 201

2

Exam 4 Chang

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Question 2 (6 points)

The following are data from a sample of minutes an individual spends outdoors per day and his or

her corresponding IQ. Using the data, provide the regression line equation.

Name Minutes Spent Outdoors Per
Day

IQ

Al 30 150

Bea 150 100

Cee 10 90

Dee 5 120

Esau 85 120

Farley 90 80

Geo 10 105

Hal 25 95

Isa 120 110

Jay 300 115

Question 3 (20 points)

You are a proud owner of three stores that sell rocking horses. You want to see if you can claim

that there is a difference in the number of rocking horses you sell in the three stores. The data are

shown below. At α = 0.05, can it be concluded that there is a difference in the number of rocking

horses sold at each store? Show EVERY STEP of the hypothesis testing procedure.

Carmel Greenwood Speedway

10 20 5

12 25

4

5 3 8

6 12 10

8 10

3

Extra Credit 3 (5 points)

Do Question 3 using the Data Analysis add-on in Excel. What is the p-value? Would your decision

change if α = 0.10?

K300 Spring 2012
Exam 4 Chang

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Question 4 (30 points)

A study is conducted to determine the relationship between a driver’s age and the number of

accidents he or she had over a one-year period. The data are shown below for 15 drivers.

Driver Age (x) Number of Accidents (y)
1 16 7

2 24 2

3 18 3

4 17 5

5 23 3

6 27 3

7 33 0

8 62 0

9 16 9

10 21 5

11 50 0

12 30 2

13 20 5

14 23 2

15 65 0

a. Compute the correlation coefficient.

b. Test the significance of the correlation coefficient at α = 0.05 using the TRADTIONAL

METHOD OF HYPOTHESIS TESTING. Show all steps.

c. Provide the regression line equation if r is significant.

d. Predict y’ for x = 33 AND x = 22. Round up to nearest whole number.

e. Find r2 and determine how much of the variation in the dependent variable is accounted for

by the variations in the independent variable.

f. Find the standard error of the estimate.

Extra Credit 4 (5 points)

Find the 95% prediction interval for the number of accidents in one year when a driver is 25 years

old, and briefly explain what it means.

K300 Spring 2012
Exam 4 Chang
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Question 5 (20 points)

We have two separate groups of 5 students who volunteered to run through an obstacle course.

Below are their times in seconds. We hypothesize that the variance in the times for Group 1 is

greater than for Group 2. At α = 0.10, is there enough evidence to support this hypothesis? USE

P-VALUE METHOD.

Group 1 Anders Bertha Callo Duff Embry
Time 15 20 10 15 8

Group 2 Isolde Jette Kelsie Lourdes Malloy

Time 8 19 13 7 10

Extra Credit 5 (5 points)

Do Question 5 using the Data Analysis add-on in Excel. What is the exact p-value? Provide a printout.