7.3-9. Consider the following two groups of women:Group 1 consists of women who spend less than $500annually on clothes; Group 2 comprises women whospend more than $1000 annually on clothes. Let p₁ andP2 equal the proportions of women in these two groups,respectively, who believe that clothes are too expensive. If1009 out of a random sample of 1230 women from group1 and 207 out of a random sample of 340 from group 2believe that clothes are too expensive,(a) Give a point estimate of pi - P2.(b) Find an approximate 95% confidence interval forP1-P2. 7.3-9 (a) 0.2115; (b) [0.1554, 0.2676].

Given that for group 1: x1 = 1009 and n1 = 1230 p1 = proportion of women in group 1 who think…

Answered: 7.3-9. Consider the following two…

A First Course in Probability (10th Edition)

10th Edition

ISBN:9780134753119

Author:Sheldon Ross

Publisher:Sheldon Ross

Chapter1: Combinatorial Analysis

Section: Chapter Questions

Problem 1.1P: a. How many different 7-place license plates are possible if the first 2 places are for letters and...

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7. Forty adult males volunteered to participate in an experiment. Half of them are randomly assigned to take a caffeine supplement before working out, and the other half are assigned to take a placebo before completing the same workout. During the workout, heart rate monitors will be used to measure each participant’s heart rate. The study found that those who took a caffeine supplement had significantly higher average pulse rates during the workout. What conclusion can be drawn from the study? (A) Two experimental groups of 20 each is too small to conclude that the results are significant. (B) Those that took the caffeine supplement had a higher average heart rate during the workout, but it would not be correct to conclude that caffeine caused this to occur. (C) The caffeine supplements caused the heart rates to increase due to the placebo effect. (D) Caffeine supplements will, on average, raise the heart rates of all adult males during a workout similar to the one performed in the…
9. A report stated that 22% of people agree that aliens exist. You conduct your own SRS study, and find that of the 95 people you interviewed, 27 agree that aliens exist. Test the claim that the percentage of people who believe in the death penalty is greater than 22%. Use a = .05. 20 18 16 14 12 10 8 6 4 2 0 0 2 6 8 10 12 14 +CDC teh hers recorded the Svalyes
1. A lawn mower company will produce 1,500 lawn mowers by 2020. In an effort to determine how much maintenance free consumers will take when they already buy lawn mowers, the company decided to conduct a study over the past 1 year of these mowers. . First, a random sample was taken by contacting 200 grass mowers. The company owner provides an 800 number and is asked to contact the company when the first repair is needed for the lawn mower. Owners who no longer use lawn mowers to cut their grass are either disqualified or not sampled. After 1 year, it turned out that 187 owners had reported for the first repair. However, the other 50 disqualified themselves. The average number per year until the first improvement was 5.3 times for samples deemed feasible. It is believed that the standard deviation is 1.28 per year. If the company wants to advertise the lawnmower and with a confidence level of 95%, what is the estimated annual mean value of repair-free lawn mower for this lawn mower?…
10. The National Institute of Mental Health published an article stating that in any one-year period, approximately 9.5 percent of American adults suffer from depression or a depressive illness. Suppose that in a survey of 100 people in a certain town, seven of them suffered from depression or a depressive illness. If you were conducting a hypothesis test to determine if the true proportion of people in that town suffering from depression or a depressive illness is lower than the percent in the general adult American population, what would the null and alternative hypotheses be? a. Ho: b. Ha
25. An egg company is studying the effects of artificial lighting on egg production of chickens. A brood of chicks were separated at random into two groups, both raised in windowless coops with artificial lighting. One group followed a natural 24-hour per day light/dark cycle while the second group experienced an accelerated 20- hour day. The weekly egg productions for the two groups are summarized in the table below. Conduct a hypothesis test to determine whether egg production is higher with a 20-hour day as compared to a 24-hour day. The level of significance is 1%. Wnat is the conclusion of the hypothesis test? Sample size Mean number of eggs Standard Deviation 24-hour day (Group 2) 20-hour day (Group 1) 45 5.2 1.8 42 6.1 2.9 A. We have enough evidence to conclude that the sample mean egg production with artificial lighting at a 20-hour day is higher than that at a 24-hour day. B. We do NOT have enough evidence to conclude that the sample mean egg production with artificial…
3. The paper "Effects of Caffeine on Repeated Sprint Ability, Reactive Agility Time, Sleep and Next Day Performance"† describes an experiment in which male athlete volunteers who were considered low caffeine consumers were assigned at random to one of two experimental groups. Those assigned to the caffeine group drank a beverage which contained caffeine 1 hour before an exercise session. Those in the no-caffeine group drank a beverage that did not contain caffeine 1 hour before an exercise session. That night, participants wore a device that measures sleep activity. The researchers reported that there was no significant difference in mean sleep duration for the two experimental groups. In the context of this experiment, explain what it means to say that there is no significant difference in the group means. A) The difference in mean sleep duration for the caffeine and no-caffeine groups could have occurred by chance just due to the random assignment, assuming there is a real difference…
1. A developmental psychologist would also like to determine how much fine motor skill improves for children from age 3 to age 4 but is worried about practice effects. She takes a random sample of 9 three-year old children and a second sample of 9 four-year olds and measures fine motor skill in each using the same test described above. Her data are provided below. Three Year Olds: 40, 35, 38, 39, 40, 50, 40, 38, 42 Four Year Olds: 35, 36, 39, 29, 35, 34, 33, 34, 35 a. Is there a significant difference in the motor skills from age three to four? Test with an α = 0.01. b. What type of error is possible based on the outcome? c. Calculate and interpret the effect size. d. What is the mean motor skill score for the age three children? What is the mean motor skill score for the age four children?
2. Suppose AB Drug Company develops a new drug, designed to prevent colds. The company states that the drug is equally effective for men and women. To test this claim, they choose a simple random sample of 100 women and 160 men from a population of 100,000 volunteers. At the end of the study, 38% of the women caught a cold; and 51% of the men caught a cold. Based on these findings, can we reject the company's claim that the drug is equally effective for men and women? Use a = 0.05 level of significance.

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