Elementary Statistics (Text Only)
2nd Edition
ISBN: 9780077836351
Author: Author
Publisher: McGraw Hill
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Chapter 10.2, Problem 17E
Defective electronics: A team of designers was given the task of reducing the defect rate in the manufacture of a certain printed circuit board. The team decided to reconfigure the cooling system. A total of 973 boards produced the week before the reconfiguration was implemented, and 254 of these were defective. A total of 847 boards were produced the week after reconfiguration, and 95 of these were defective.
- Construct a 90% confidence inters-al for the decrease in the defective rate after the reconfiguration.
- A quality control engineer claims that the reconfiguration has decreased the proportion of defective parts by more than 0.15. Does the confidence interval contradict this claim?
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8.2
Question 3). According to the February 2008 Federal Trade Commission report on consumer fraud and identity theft, Arkansas had 1,601 complaints of identity theft out of 3,482 consumer complaints ("Consumer fraud and," 2008). Calculate a 90% confidence interval for the proportion of identity theft in Arkansas.
The heart rate variability (HRV) of police officers was the subject of research published in a biology journal. HRV is defined as the variation in the time intervals between heartbeats. A measure of HRV was obtained for each in a sample of 331
police officers from the same city. (The lower the measure of HRV, the more susceptible the officer is to cardiovascular disease.) For the 76 officers diagnosed with hypertension, a 90% confidence interval for the mean HRV was (7.2,121.3). For
the 255 officers that are not hypertensive, a 90% confidence interval for the mean HRV was (141.6,189.9). Use this information to complete parts a through d below.
a. What confidence coefficient was used to generate the confidence intervals?
(Type an integer or a decimal. Do not round)
b. Give a practical interpretation of both of the 90% confidence intervals. Use the phrase '90% confident" in your answer.
The researchers can be 90% confident that the
Type integers or decimals. Do not round.)
V mean HRV for…
A U.S. Food Survey showed that Americans routinely eat beef in their diet. Suppose that in a study of 49 consumers in Illinois and 64 consumers in Texas the following results were obtained from two samples regarding average yearly beef consumption:
Illinois Texas
= 49 = 64
= 54.1lb = 60.4lb
S1 = 7.0 S2 = 8.0
Develop a 95% confidence Interval Estimate for the difference between the two population means.
Chapter 10 Solutions
Elementary Statistics (Text Only)
Ch. 10.1 - In Exercises 5 and 6, fill in each blank with e...Ch. 10.1 - In Exercises 5 and 6, fill in each blank with e...Ch. 10.1 - Prob. 7ECh. 10.1 - Prob. 8ECh. 10.1 - In Exercises 9-14, construct the confidence...Ch. 10.1 - Prob. 10ECh. 10.1 - In Exercises 9-14, construct the confidence...Ch. 10.1 - Prob. 12ECh. 10.1 - Prob. 13ECh. 10.1 - Prob. 14E
Ch. 10.1 - Does this diet help? A group of 78 people enrolled...Ch. 10.1 - Contaminated water: The concentration of benzene...Ch. 10.1 - Fertilizer: In an agricultural experiment, the...Ch. 10.1 - Computer crashes: A computer system administrator...Ch. 10.1 - Are you smarter than your older brother? In a...Ch. 10.1 - Effectiveness of distance learning: A study was...Ch. 10.1 - Boys and girls: The National Health Statistics...Ch. 10.1 - Body mass index: In a survey of adults with...Ch. 10.1 - Energy drinks: A survey of college students...Ch. 10.1 - Low-fat or low-carb? Are low-fat diets or low-carb...Ch. 10.1 - Online testing: Do you prefer taking tests on...Ch. 10.1 - Drive safely: How often does the average driver...Ch. 10.1 - Interpret calculator display: The following TI-84...Ch. 10.1 - Prob. 28ECh. 10.1 - Prob. 29ECh. 10.1 - Prob. 30ECh. 10.1 - Prob. 31ECh. 10.2 - In Exercises 3 and 4, fill in each blank with the...Ch. 10.2 - Prob. 4ECh. 10.2 - Prob. 5ECh. 10.2 - Prob. 6ECh. 10.2 - In Exercises 7-12, construct the confidence...Ch. 10.2 - In Exercises 7-12, construct the confidence...Ch. 10.2 - In Exercises 7-12, construct the confidence...Ch. 10.2 - In Exercises 7-12, construct the confidence...Ch. 10.2 - In Exercises 7-12, construct the confidence...Ch. 10.2 - Prob. 12ECh. 10.2 - Traffic accidents: Traffic engineers compared...Ch. 10.2 - Computers in the classroom: In a new experimental...Ch. 10.2 - Pain after surgery: In a random sample of 50...Ch. 10.2 - Pretzels: In order to judge the effectiveness of...Ch. 10.2 - Defective electronics: A team of designers was...Ch. 10.2 - Prob. 18ECh. 10.2 - Cancer prevention: Colonoscopy is a medical...Ch. 10.2 - Social media: A Pew poll found that in a sample of...Ch. 10.2 - Interpret calculator display: The following TI-84...Ch. 10.2 - Prob. 22ECh. 10.2 - Prob. 23ECh. 10.2 - Prob. 24ECh. 10.2 - Finding the sample size: Polls are to be conducted...Ch. 10.3 - In Exercises 3 and 4, fill in each blank with the...Ch. 10.3 - Prob. 4ECh. 10.3 - Prob. 5ECh. 10.3 - In Exercises 5 and 6, determine whether the...Ch. 10.3 - Fast computer: microprocessors are compared on a...Ch. 10.3 - Brake wear: For a sample of 9 automobiles, the...Ch. 10.3 - Strength of concrete: The compressive strength, m...Ch. 10.3 - Truck pollution: In an experiment to determine the...Ch. 10.3 - High cholesterol: A group of eight individuals...Ch. 10.3 - Tires and fuel economy: A tire manufacturer is...Ch. 10.3 - Prob. 13ECh. 10.3 - Prob. 14ECh. 10.3 - Interpret calculator display: The following TI-84...Ch. 10.3 - Interpret calculator display: The following TI-84...Ch. 10.3 - Prob. 17ECh. 10.3 - Prob. 18ECh. 10.3 - Advantage of matched pairs: Refer to Exercise 12....Ch. 10.3 - Paired or independent? To construct a confidence...Ch. 10 - In Exercises 1 and 2, determine whether the...Ch. 10 - Prob. 2CQCh. 10 - Prob. 3CQCh. 10 - Prob. 4CQCh. 10 - Prob. 5CQCh. 10 - Prob. 6CQCh. 10 - Prob. 7CQCh. 10 - Prob. 8CQCh. 10 - Prob. 9CQCh. 10 - Prob. 10CQCh. 10 - Prob. 11CQCh. 10 - Refer to Exercise 11. Find the critical value for...Ch. 10 - Prob. 13CQCh. 10 - Prob. 14CQCh. 10 - Prob. 15CQCh. 10 - Prob. 1RECh. 10 - Prob. 2RECh. 10 - Prob. 3RECh. 10 - Prob. 4RECh. 10 - Prob. 5RECh. 10 - Prob. 6RECh. 10 - Prob. 7RECh. 10 - Prob. 8RECh. 10 - Prob. 9RECh. 10 - Prob. 10RECh. 10 - Prob. 11RECh. 10 - Prob. 12RECh. 10 - Prob. 13RECh. 10 - Prob. 14RECh. 10 - Prob. 15RECh. 10 - Prob. 1WAICh. 10 - Prob. 2WAICh. 10 - Prob. 3WAICh. 10 - Prob. 4WAICh. 10 - Prob. 1CSCh. 10 - Prob. 2CSCh. 10 - Prob. 3CS
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