Brase and Brase - Understandable Statistics 9/e (Homework)

James Finch

Statistics, Fall 2010

Instructor: Dr. Friendly

Current Score: 19/40

Due: Wednesday, October 20, 2010 23:00 EDT

About this Assignment

Ask Your Teacher popUp

Extension Requests popUp

Question

Points

1	2	3	4	5	6	7
0/1	3	7	9	0/7	0/4	0/9

Total

19/40

Description

Here are some textbook questions from Understandable Statistics: Concepts and Methods 9/e by Charles Henry Brase and Corinne Pellillo Brase published by Brooks/Cole. Click here for a list of all of the questions coded in WebAssign.

Instructions

This demo assignment allows many submissions and allows you to try another version of the same question for practice.

1. 0/1 points All Submissions Notes Question: BBUnderStat9 2.2.012.

Question part

Points

Submissions

1
0/1
5/50

Total

0/1

How does average height for boys change as boys get older? According to Physician's Handbook, the average heights at different ages are in the table below.

Age (years)	0.5	1	2	3	4	5	6	7	8	9	10	11
Height (inches)	26	29	33	36	39	42	45	47	50	52	54	56

Make a time-series graph for average height for ages 0.5 through 11 years. (Plot both points and lines.)

Flash Player version 10 or higher is required for this question.
You can get Flash Player free from Adobe's website.

Need Help?

2. 3/3 points All Submissions Notes Question: BBUnderStat9 3.1.004.

Question part

Points

Submissions

1	2	3
1	1	1
5/50	1/50	5/50

Total

3/3

Consider the following types of data that were obtained from a random sample of 49 credit card accounts. Identify all the averages (mean, median, or mode) that can be used to summarize the data. (Select all that apply.)

Need Help?

3. 7/7 points All Submissions Notes Question: BBUnderStat9 3.1.006.SBS.

Question part

Points

Submissions

1	2	3	4	5	6	7
1	1	1	1	1	1	1
1/50	1/50	4/50	1/50	1/50	3/50	2/50

Total

7/7

In this problem, we explore the effect on the mean, median, and mode of adding the same number to each data value. Consider the following data set.

1, 1, 2, 5, 9

STEP 1:

Compute the mode, median, and mean.

mode	Enter an exact number. 1
median	Enter an exact number. 2
mean	Enter a number. 3

STEP 2:

Add 6 to each of the data values. Compute the mode, median, and mean.

mode	Enter an exact number. 4
median	Enter an exact number. 5
mean	Enter a number. 6

STEP 3:

Compare the results of parts (a) and (b). In general, how do you think the mode, median, and mean are affected when the same constant is added to each data value in a set?

Adding the same constant c to each data value results in the mode, median, and mean remaining the same. Adding the same constant c to each data value results in the mode, median, and mean increasing by c units. Adding the same constant c to each data value results in the mode, median, and mean decreasing by c units. There is no distinct pattern when the same constant is added to each data value in a set.

Your answer is correct.

Need Help?

4. 9/9 points All Submissions Notes Question: BBUnderStat9 3.2.011.

Question part

Points

Submissions

1	2	3	4	5	6	7	8	9
1	1	1	1	1	1	1	1	1
1/50	1/50	1/50	1/50	1/50	1/50	1/50	1/50	1/50

Total

9/9

Kevlar epoxy is a material used on the NASA Space Shuttle. Strands of this epoxy were tested at the 90% breaking strength. The following data represent time to failure (in hours) for a random sample of 50 epoxy strands (Reference: R. E. Barlow, University of California, Berkeley). Let x be a random variable representing time to failure (in hours) at 90% breaking strength. Note: These data are also available for download online in HM StatSPACE^TM.

0.86	0.23	3.33	1.22	0.5	0.32	0.89	1.94	1.1	0.38
1.43	0.62	0.71	1.1	0.65	0.17	3.9	1.58	0.86	0.8
0.98	0.65	0.65	3.45	1.79	7.61	1.64	1.64	1.43	1.19
1.43	1.91	1.07	0.95	1.7	1.22	0.29	1.04	1.19	1.37
1.28	0.29	1.49	0.47	1.34	0.71	0.59	1.19	1.55	0.8

(a) Find the range. (Enter your answer to 2 decimal places.)
Your answer is correct.

(b) Use a calculator to calculate Σx and Σx².

Σx	Enter a number. 2
Σx²	Enter a number. 3

(c) Use the results of part (b) to compute the sample mean, variance, and standard deviation for the time to failure. (Enter your answers to 2 decimal places.)

x	Enter a number. 4
s²	Enter a number. 5
s	Enter a number. 6

(d) Use the results of part (c) to compute the coefficient of variation. (Enter your answer to one decimal place.)
Your answer is correct.

%

What does this number say about time to failure?

The standard deviation of the time to failure is just slightly smaller than the average time. The coefficient of variation says nothing about time to failure. The standard deviation of the time to failure is just slightly larger than the average time. The standard deviation is equal to the average.

Your answer is correct.

Why does a small CV indicate more consistent data, whereas a larger CV indicates less consistent data? Explain.

A small CV indicates more consistent data because the value of s in the numerator is smaller. A small CV indicates more consistent data because the value of s in the numerator is larger.

Your answer is correct.

Need Help?

5. –/7 points Notes Question: BBUnderStat9 4.1.009.

Question part

Points

Submissions

1	2	3	4	5	6	7
0/1	0/1	0/1	0/1	0/1	0/1	0/1
0/50	0/50	0/50	0/50	0/50	0/50	0/50

Total

0/7

Isabel Briggs Myers was a pioneer in the study of personality types. The personality types are broadly defined according to four main preferences. Do married couples choose similar or different personality types in their mates? The following data give an indication (Source: I. B. Myers and M. H. McCaulley, A Guide to the Development and Use of the Myers-Briggs Type Indicators).

Similarities and Differences in a Random Sample of 375 Married Couples
Number of Similar Preferences	Number of Married Couples
All four Three Two One None	33 135 125 62 20

Suppose that a married couple is selected at random.

(a) Use the data to estimate the probability that they will have 0, 1, 2, 3, or 4 personality preferences in common. (Enter your answers to 2 decimal places.)

0	1	2	3	4
Enter a number. 1	Enter a number. 2	Enter a number. 3	Enter a number. 4	Enter a number. 5

(b) Do the probabilities add up to 1? Why should they?

Yes, because they do not cover the entire sample space. No, because they do not cover the entire sample space. Yes, because they cover the entire sample space. No, because they cover the entire sample space.

What is the sample space in this problem?

0, 1, 2, 3 personality preferences in common 1, 2, 3, 4 personality preferences in common 0, 1, 2, 3, 4, 5 personality preferences in common 0, 1, 2, 3, 4 personality preferences in common

Need Help?

6. –/4 points Notes Question: BBUnderStat9 4.2.011.

Question part

Points

Submissions

1	2	3	4
0/1	0/1	0/1	0/1
0/50	0/50	0/50	0/50

Total

0/4

You roll two fair dice, a green one and a red one.

(a) What is the probability of getting a sum of 6? (Use 3 decimal places.)

(b) What is the probability of getting a sum of 4? (Use 3 decimal places.)

(c) What is the probability of getting a sum of 6 or 4? (Use 3 decimal places.)

Are these outcomes mutually exclusive?

yes no

Need Help?

7. –/9 points Notes Question: BBUnderStat9 4.2.024.

Question part

Points

Submissions

1	2	3	4	5	6	7	8	9
0/1	0/1	0/1	0/1	0/1	0/1	0/1	0/1	0/1
0/50	0/50	0/50	0/50	0/50	0/50	0/50	0/50	0/50

Total

0/9

Are customers more loyal in the East or in the West? The following table is based on information from Trends in the United States, published by the Food Marketing Institute, Washington, D.C. The columns represent length of customer loyalty (in years) at a primary supermarket. The rows represent regions of the United States.

	Less Than 1 Year	1-2 Years	3-4 Years	5-9 Years	10-14 Years	15 or More Years	Row Total
East	32	59	59	112	77	132	471
Midwest	31	76	68	120	63	174	532
South	53	78	93	158	106	196	684
West	41	52	67	78	45	96	379
Column Total	157	265	287	468	291	598	2066

(a) What is the probability that a customer chosen at random has been loyal 10 to 14 years? (Use 3 decimal places for all answers.)

(b) What is the probability that a customer chosen at random has been loyal 10 to 14 years, given that he or she is from the East?

(c) What is the probability that a customer chosen at random has been loyal at least 10 years?

(d) What is the probability that a customer chosen at random has been loyal at least 10 years, given that he or she is from the West?

(e) What is the probability that a customer chosen at random is from the West, given that he or she has been loyal less than 1 year?

(f) What is the probability that a customer chosen at random is from the South, given that he or she has been loyal less than 1 year?

(g) What is the probability that a customer chosen at random has been loyal 1 or more years, given that he or she is from the East?

(h) What is the probability that a customer chosen at random has been loyal 1 or more years, given that he or she is from the West?

(i) Are the events from the East and loyal 15 or more years independent? Explain.

Yes. These events can occur together. No. P(loyal 15 or more years) ≠ P(loyal 15 or more years | East). Yes. P(loyal 15 or more years) = P(loyal 15 or more years | East). No. These events cannot occur together.

Need Help?

WebAssign

Logged in as demo@demo

Brase and Brase - Understandable Statistics 9/e (Homework)

Current Score: 19/40