Due Friday, December 4, 2009
Homework is due on the due date at the end of the lecture.
Reading:
November 16 –
November 18 – November 20
November 30 – December 4
Chapter 18 (pages 466 – 477)
Chapter 23
Chapters 24, 25
Assignment:
1.
Do the following problems from the text, Intro Stats , 3 rd Edition. If you have an earlier edition of the text, check with someone who has the 3 rd Edition to make sure you do the correct problems. a) Chapter 18 – problems 29, 30, 31, and 32. b) Chapter 23 – problems 1, 2, 5, 6, 15, 31, and 37.
2.
In a study of youths in the East Boston area, several different measurements were made on boys age 3 to 13. Below are the heights (inches) of 25 randomly selected boys from East Boston.
59 52 59 69 58.5 57.5
54 64.5
53 47 61 71 52
61 55.5 62 56.5 60.5
65 59.5 61.5
68 65 60.5 51.5
n
= 25 , y
= 59 .
36 , s
= 5 .
89
3
.99
.95
.90
.75
2
1
0 .50
.25
.10
.05
.01
-1
-2
-3
45 50 55 60
Height
65 70 75
6
4
2
1

a) Verify that the conditions for statistical inference are met. b) Construct a 95% confidence interval for the mean height of all boys in
East Boston age 3 to 13. c) Give an interpretation of this confidence interval. d) Is 60 inches a plausible value for the mean height of boys age 3 to 13 in
East Boston? Support your answer by referring to the confidence interval you constructed in b).
3.
The local grocery store packages different grades (based on fat content) of hamburger.
Usually the leaner (less fat) grades are more expensive. A simple random sample of 12 one-pound packages of hamburger is obtained from the local store and tested for fat content. Below are the percentages of lean meat for each package.
90.7 94.1 91.7 92.3 91.6 93.2 91.4 92.4 92.1 93.4 92.9 93.0 a) Calculate the sample mean percentage of lean meat and the sample standard deviation. b) The packages are labeled 93% lean. Use the summaries in a) to test the hypothesis H
0
: μ = 93 against H
A
: μ < 93, where μ is the population mean percentage lean. Be sure to calculate the appropriate test statistic and P-value, reach a decision and justify that decision, and state a conclusion. c) Based on the test in b), are the packages labeled correctly? Explain briefly. d) One of the conditions for the test in b) is that the random sample could have come from a population described by a normal model (the nearly normal condition). Use the sample data to construct a box plot. Does the shape of the box plot support the nearly normal condition? Explain briefly.
4.
Earlier in the semester on homework #3 data on body temperature were given. A
JMP file on the course web page (BodyTemp.JMP) contains data on the body temperature ( o F) for 130 randomly selected individuals. Use JMP to construct a
90% confidence interval and test the hypothesis that the population mean body temperature is 98.6 o F. Turn in the JMP output with your answer to the following. a) Construct a 90% confidence interval for the population mean body temperature. Give an interpretation of this interval. b) Test the hypothesis that the population mean body temperature is 98.6 o F against the alternative that the population mean body temperatures is different from 98.6 o F. Be sure to include all steps for the test of hypothesis.
2