In a study conducted by some researchers, 82 people were randomly assigned to listen to rap music or music by Mozart while attempting to memorize objects pictured on a page. They were then asked to list all the objects they could remember. For the difference (rap minus Mozart) in the mean numbers of objects remembered, researchers obtained a point estimate of 0.176 and a standard error of 0.968. Construct a 90% two-sided confidence interval for this difference and put its upper endpoint into the box below. Your Answer: Answer

The principal at a large high school claims that students spend at least 10 hours per week doing homework, on average. To investigate this claim, an AP Statistics class selected a random sample of 250 students from their school and asked them how long they spent doing homework during the last week. The sample mean was 10.2 hours and the sample standard deviation was 4.2 hours. Construct and interpret a 95% confidence interval for the mean time that students at this school spent doing homework in the last week. Based on your interval, what can you conclude about the principal's claim? What is your t* value? Remember to use the conservative DF value.

A study of 40 English professors showed that they spend, on average, 12.6 minutes correcting a student's term paper. The standard deviation was 2.5 minutes. Construct the 99% confidence interval of the mean for all term papers.

A survey of 2450 golfers showed that 281 of them are left-handed. Construct a 90% confidence interval for the proportion of golfers that are left-handed. Question 10 options: (0.104, 0.125) (0.369, 0.451) (0.100, 0.130) (0.203, 0.293)

A research company is interested in determining the true proportion of Americans that work remotely. In a random sample of 200 individuals, 4.5% of them work remotely. Find a 90% confidence interval for the true proportion of Americans that work remotely.

A survey of 3737 randomly selected homeowners finds that they spend a mean of $73$73 per month on home maintenance with a standard deviation of $10$10 per month.   Construct a 90%90% confidence interval for the mean amount of money spent per month on home maintenance by all homeowners. Round to the nearest cent.

A sports news station wanted to know whether people who live in the North or the South are bigger sports fans. For its study, 121 randomly selected Southerners were surveyed and found to watch a mean of 4.6 hours of sports per week. In the North, 176 randomly selected people were surveyed and found to watch a mean of 3.2 hours of sports per week. Find a 90% confidence interval for the true difference between the mean numbers of hours of sports watched per week for the two regions if the South has a population standard deviation of 1.6 hours per week and the North has a population standard deviation of 1.4 hours per week. Let Population 1 be people who live in the South and Population 2 be people who live in the North. Round the endpoints of the interval to one decimal place, if necessary. Lower endpoint: Upper endpoint:

In a study designed to determine whether there was a cluster of brain cancer cases at a Pratt & Whitney plant, record from 223,000 employees were studied and 723 employees with brain tumors were found. Treat those employees as a random sample and construct a 95% confidence interval estimate of the proportion of all adults who develop such tumors. write a brief statement interpreting that confidence interval.

8.2 question 5).  In 2013, the Gallup poll asked 1,039 American adults if they believe there was a conspiracy in the assassination of President Kennedy and found that 634 believe there was a conspiracy ("Gallup news service," 2013). Estimate the proportion of American’s who believe in this conspiracy using a 98% confidence interval.

In September a biological research team caught, weighed, and released a random sample of 24 chipmunks in Rocky Mountain National Park. The mean of the sample weights was x-bar = 8.7 oz. with sample standard deviation s = 1.4 oz. Find a 90% confidence interval for the mean September weight of all chipmunks in Rocky Mountain National Park.