In a survey, two independent random samples of workers of sizes m = 124 and n = 130 from two construction firms, were asked if they wear security helmets all the time. In the first sample 106 said yes, while in the second 98 said yes. Let p1 and p2 be the population proportions of workers of the two firms who wear their security helmets all the time. Test the equality of p1 and p2 at a = 0.05 (large sample procedure), by the same 5 steps as before.  Construct a large sample 90% confidence interval for p1 – p2.

An airport official wants to prove that the proportion of delayed flights for Airline A (denoted as p1) is less than the proportion of delayed flights for Airline B (denoted as p2). Random samples for both airlines after a storm showed that 51 out of 200 flights for Airline A were delayed, while 60 out of 200 of Airline B's flights were delayed. The test statistic for this problem is -1.00. The p-value for the test statistic for this problem is: p = 0.0228 p = 0.0668 p = 0.3413 p = 0.1587

According to a certain government agency for a large country, the proportion of fatal traffic accidents in the country in which the driver had a positive blood alcohol concentration (BAC) is 0.38. Suppose a random sample of 105 traffic fatalities in a certain region results in 51 that involved a positive BAC. Does the sample evidence suggest that the region has a higher proportion of traffic fatalities involving a positive BAC than the country at the a = 0.01 level of significance? Because npo (1 - Po 10, the sample size is 5% of the population size, and the sample the requirements for testing the hypothesis satisfied. (Round to one decimal place as needed.) can be reasonably assumed to be random, What are the null and alternative hypotheses? is given to be random, cannot be reasonably assumed to be random, Ho: versus H,: (Type integers or decimals. Do not round.) is given to not be random, Find the test statistic, zo. Z0 = (Round to two decimal places as needed.) Find the P-value.…

A private and a public university are located in the same city. For the private university, 1042 alumni were surveyed and 655 said that they attended at least one class reunion. For the public university, 804 out of 1317 sampled alumni claimed they have attended at least one class reunion. Is the difference in the sample proportions statistically significant? (Use α=0.05) a) Reject the null hypothesis which states there is no difference in the proportion of alumni that attended at least one class reunion in favor of the alternate which states there is a difference in the proportions. b) Fail to reject the null hypothesis. There is not enough evidence to conclude that there is a difference in the proportions. c) There is not enough information to make a conclusion.

A lawn mower company will produce 1,500 lawn mowers by 2020. In an effort to determine how much maintenance-free consumers will buy when they 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 74 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? What is the…

According to a certain government agency for a large country, the proportion of fatal traffic accidents in the country in which the driver had a positive blood alcohol concentration (BAC) is 0.34. Suppose a random sample of 109 traffic fatalities in a certain region results in 50 that involved a positive BAC. Does the sample evidence suggest that the region has a higher proportion of traffic fatalities involving a positive BAC than the country at the x = 0.01 level of significance? Because npo (1-Po) = 24.5 > 10, the sample size is (Round to one decimal place as needed.) What are the null and alternative hypotheses? p = 0.34 versus H₁: p > 0.34 Ho: p (Type integers or decimals. Do not round.) Find the test statistic, Zo. Zo = 2.62 (Round to two decimal places as needed.) Find the P-value. P-value = (Round to three decimal places as needed.) less than 5% of the population size, and the sample is given to be random, the requirements for testing the hypothesis are satisfied.

The Substance Abuse and Mental Health Services Administration (SAMHSA, 2017) estimates that 10.9% of the population of the United States age 18–24 had an episode of depression in the previous 12 months. Suppose a researcher takes a random sample of 225 United States adults aged 18–24. Determine the value of the sample proportion, p, such that 5% of samples of 225 United States adults age 18–24 are greater than p. You may find software or a z-table useful. Give your answer precise to three decimal places. p = II

A local cellular phone company wishes to estimate the proportion of Clinton County people who own a cellular phone. A previous study showed the proportion to be about 25%. What is the minimum number of people that should be randomly selected so the cellular company is 95% confident that the estimate is within 5% of the true proportion of cellular phone users?

A demographer wants to know what proportion of women in different countries dye their hair. They take a random sample of women from Korea and another random sample of women from China. In Korea, 47% dyed their hair. In China, 56% dyed their hair. (a) What hypotheses would the demographer use to test if women in China are more likely to dye their hair than women in Korea? H0: pChina=pKorea vs. Ha: pChina ≠ pKoreaH0: pChina - pKorea = 0 vs. Ha: pChina - pKorea > 0    H0: μChina-μKorea = 0 vs. Ha: μChina-μKorea ≠ 0H0: pChina-pKorea = 0.09 vs. Ha: pChina-pKorea ≠ 0.09H0: μChina = 0.56 vs. Ha: μKorea = 0.47 (b) Suppose their test yielded a p-value of 0.079. What does this mean in the context of the test? We are 7.9% confident that the results of our test are correct.If the women of two countries have the same rates of coloring their hair, the probability of getting a difference at least this large is 0.079.    If we take another sample, the probability of getting the same p̂China and…

The news release referenced in the previous exercise also included data fromindependent samples of teenage drivers and parents of teenage drivers. In response to aquestion asking if they approved of laws banning the use of cell phones and texting whiledriving, 74% of the teens surveyed and 95% of the parents surveyed said they approved.The sample sizes were not given in the news release, but suppose that 600 teens and 400 parents of teens were surveyed and that these samples are representative of the twopopulations. Do the data provide convincing evidence that the proportion of teens whoapprove of banning cell phone and texting while driving is less than the proportion ofparents of teens who approve?