10.18 A large retail lawn care dealer currently provides a 2-year warranty on all lawn mowerssold at its stores. A new employee suggested that the dealer could save money by just not offeringthe warranty. To evaluate this suggestion, the dealer randomly decides whether or not to offerthe warranty to the next 50 customers who enter the store and express an interest in purchasinga lawnmower. Out of the 25 customers offered the warranty, 10 purchased a mower as comparedto 4 of 25 not offered the warranty.a. Place a 95% confidence interval on π,-T2, the difference in the proportions ofcustomers purchasing lawnmowers with and without the warranty.b. Test the research hypothesis that offering the warranty will increase the propor-tion of customers who will purchase a mower. Use α-,05.

a.Confidence Interval:The form of the confidence interval is,CI = Point estimate ± Margin of…

Answered: 10.18 A large retail lawn care dealer…

Holt Mcdougal Larson Pre-algebra: Student Edition 2012

1st Edition

ISBN:9780547587776

Author:HOLT MCDOUGAL

Publisher:HOLT MCDOUGAL

Chapter11: Data Analysis And Probability

Section: Chapter Questions

Problem 8CR

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Do well-rounded people get fewer colds? A study on the Chronicle of Higher Education was conducted by scientist at Carnegie Mellon University, the University of Pittsburgh and the University of Virginia. They found that people who have only a few social outlets get more colds than those who are involved in a variety of social activities. Suppose that of the 276 healthy men and women tested, n1=96 had only a few social outlets and n2=105 were busy with six or more activities. When these people were exposed to a cold virus, the following results were observed: Construct a 99% confidence interval for the difference in the two population proportions.
According to a local chamber of commerce, in 1993, 5.9% of local area residents owned more than five cars. A local car dealer claims that the percentage has increased. He randomly selects 180 local area residents and finds that 12 of them own more than five cars. Test this car dealer's claim at the level of significance of 0.05.
Suppose a research study uses two independent groups with 21 individuals in each group. If a t-test analysis produces a calculated value of t of 1.68, which of the following is the correct decision?A. At the .05 level of significance, reject the null hypothesisB. At the .01 level of significance, reject the null hypothesisC. At the .05 level of significance, fail to reject the null hypothesisD. Impossible to answer without additional information
In a previous poll, 42% of adults with children under the age of 18 reported that their family ate dinner together seven nights a week. Suppose that, in a more recent poll, of 1060 adults with children under the age of 18 reported that their family ate dinner together seven nights a week.dinner together seven nights a week. Suppose that, in a more recent poll, 423 of 1060adults with children under the age of 18 reported that their family ate dinner together seven nights a week. Is there sufficient evidence that the proportion of families with children under the age of 18 who eat dinner together seven nights a week has decreased? Use the α=0.01 significance level. (a) What are the null and alternative hypotheses? (b) H0 versus H1 (c) Find the test statistic, z0. (d) Find the P-value. Is there sufficient evidence that the proportion of families with children under the age of 18 who eat dinner together seven nights a week has decreased?
2.Are babies born to mothers who use assistive reproduction technology (ART) more likely to be born prematurely than babies conceivednaturally? The data in the accompanying table are from a random sample of 19,614 births. Each birth was classified according to whether the mother used ART and whether the baby was premature. Use these data to decide if there is convincing evidence of an association between the use of ART and whether or not a baby ispremature. Use?=0.05.ConceivedUsing ARTConceivedNaturallyPremature1542,405Not Premature21218,843 Hypotheses: Method:Q:__________________S:__________________T:__________________N:__________________ Check: Calculate: Communicate Results:
A study conducted in a certain period of time found that fewer than half of employers who hired new college graduates last academic year plan to definitely do so again. Suppose that the hiring intentions of the respondents were as follows: 32% selected Hire 29% selected Likely to Hire 21% selected Hire Uncertain 18% selected Do Not Hire Six month later, a random sample of 100 employers were asked about their hiring intentions and gave the following responses: 29 selected Hire 35 selected Likely to Hire 14 selected Hire Uncertain 22 selected Do Not Hire At 1% significance level, does it mean that proportions from the initial study have significantly changed? Use Goodness-of-Fit test and χ2χ2 distribution. For part (a), round your answers in the " (O−E)2E(O-E)2E" column to 3 decimal places. (a) Fill in the table below. Hiring Intention Observed Frequency OO Expected Frequency EE O−EO-E (O−E)2(O-E)2 (O−E)2E(O-E)2E Hire 29 Likely to Hire 35 Hire…
10.19. A random survey was conducted among voting-age citizens to determine whether there was any relationship between party affiliation and opinion regarding gun control. The information provided in Table 10.7 was obtained. For α = 0.01, is there any reason to believe that there is a dependence between opinion and party affiliation? Table 10.7 Party affiliation and opinions on gun control. In favor Against Undecided Democrats 110 64 26 Republicans 90 116 14 Independents 55 35 10
A random sample of n1 = 10 regions in New England gave the following violent crime rates (per million population). x1: New England Crime Rate 3.3 3.7 4.2 3.9 3.3 4.1 1.8 4.8 2.9 3.1 Another random sample of n2 = 12 regions in the Rocky Mountain states gave the following violent crime rates (per million population). x2: Rocky Mountain Crime Rate 3.5 4.1 4.7 5.5 3.3 4.8 3.5 2.4 3.1 3.5 5.2 2.8 Assume that the crime rate distribution is approximately normal in both regions. Do the data indicate that the violent crime rate in the Rocky Mountain region is higher than in New England? Use ? = 0.01. Solve the problem using both the traditional method and the P-value method. (Test the difference ?1 − ?2. Round the test statistic and critical value to three decimal places.) test statistic critical value Find (or estimate) the P-value. A. P-value > 0.250 B. 0.125 < P-value < 0.250 C. 0.050 < P-value < 0.125 D. 0.025 < P-value <…
A random sample of n1 = 10 regions in New England gave the following violent crime rates (per million population). x1: New England Crime Rate 3.3 3.7 4.0 3.9 3.3 4.1 1.8 4.8 2.9 3.1 Another random sample of n2 = 12 regions in the Rocky Mountain states gave the following violent crime rates (per million population). x2: Rocky Mountain Crime Rate 3.5 4.3 4.5 5.1 3.3 4.8 3.5 2.4 3.1 3.5 5.2 2.8 Assume that the crime rate distribution is approximately normal in both regions. (i) Use a calculator to calculate x1, s1, x2, and s2. (Round your answers to three decimal places.) x1 = s1 = x2 = s2 = (ii) Do the data indicate that the violent crime rate in the Rocky Mountain region is higher than in New England? Use α = 0.01.(a) What is the level of significance? What is the value of the sample test statistic? (Test the difference μ1 − μ2. Round your answer to three decimal places.)
suppose that from a sample of 200,000 new york workers, 32,400 reported traveling more than an hour an day. From this information, statisticians determined that about 16.2% of the workers in the state traveled more than an hou to work every day in 2011. If there were 8,437,512 workers in the entire population, about how many traveled more than an hour to work each day?
A random sample of n1 = 10 regions in New England gave the following violent crime rates (per million population). x1: New England Crime Rate 3.3 3.7 4.2 3.9 3.3 4.1 1.8 4.8 2.9 3.1 Another random sample of n2 = 12 regions in the Rocky Mountain states gave the following violent crime rates (per million population). x2: Rocky Mountain Crime Rate 3.9 4.1 4.5 5.5 3.3 4.8 3.5 2.4 3.1 3.5 5.2 2.8 Assume that the crime rate distribution is approximately normal in both regions. Do the data indicate that the violent crime rate in the Rocky Mountain region is higher than in New England? Use ? = 0.01. Solve the problem using both the traditional method and the P-value method. (Test the difference ?1 − ?2. Round the test statistic and critical value to three decimal places.) test statistic critical value
A random sample of n1 = 10 regions in New England gave the following violent crime rates (per million population). x1: New England Crime Rate 3.5 3.7 4.2 3.9 3.3 4.1 1.8 4.8 2.9 3.1 Another random sample of n2 = 12 regions in the Rocky Mountain states gave the following violent crime rates (per million population). x2: Rocky Mountain Crime Rate 3.9 4.1 4.5 5.1 3.3 4.8 3.5 2.4 3.1 3.5 5.2 2.8 Assume that the crime rate distribution is approximately normal in both regions. (a) Use a calculator to calculate x1, s1, x2, and s2. (Round your answers to four decimal places.) x1=s1=x2=s2= (b) Do the data indicate that the violent crime rate in the Rocky Mountain region is higher than in New England? Use ? = 0.01. (i) What is the level of significance? State the null and alternate hypotheses. H0: ?1 = ?2; H1: ?1 ≠ ?2H0: ?1 = ?2; H1: ?1 > ?2 H0: ?1 < ?2; H1: ?1 = ?2H0: ?1 = ?2; H1: ?1 < ?2 (ii) What sampling distribution will you use? What…

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