Exam 10: Inference About Means and Proportions With Two Populations

The results of a recent poll on the preference of shoppers regarding two products are shown below. ​ At 95% confidence, the margin of error is

The following are the results about the test scores of two samples of students from University A and University B on a national statistics examination.The population standard deviations are also shown below.Develop a 95% confidence interval estimate for the difference between the mean scores of the two populations.

An insurance company selected samples of clients under 18 years of age and over 18 and recorded the number of accidents they had in the previous year.The results are shown below. ​ We are interested in determining if the accident proportions differ between the two age groups.The p-value is

A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics today and those enrolled five years ago.A sample of final examination scores from students enrolled today and from students enrolled five years ago was taken.You are given the following information. ​ The 98% confidence interval for the difference between the two population means is

A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics today and those enrolled five years ago.A sample of final examination scores from students enrolled today and from students enrolled five years ago was taken.You are given the following information. ​ The p-value for the difference between the two population means is

Using the following data regarding the ages (in years) of full-time and part-time students, develop an interval estimate for the difference between the mean ages of the two populations.Use 95% confidence.The degrees of freedom for the t distribution is 106. ​

A comparative study of organic and conventionally grown produce was checked for the presence of E.coli.Results are summarized below.Is there a significant difference in the proportion of E.coli in organic vs.conventionally grown produce? Test at α = .10.

In a sample of 100 Republicans, 60 favored the President's anti-drug program.While in a sample of 150 Democrats, 84 favored his program.At α = .05, test to see if there is a significant difference in the proportions of the Democrats and the Republicans who favored the President's anti-drug program.

The results of a recent poll on the preference of shoppers regarding two products are shown below. ​ The 95% confidence interval estimate for the difference between the populations favoring the products is

Two independent simple random samples are taken to test the difference between the means of two populations whose variances are not known, but are assumed to be equal.The sample sizes are n₁ = 31 and n₂ = 40.The correct distribution to use is the t distribution with _____ degrees of freedom.

The following information was obtained from independent random samples taken of two populations. Assume normally distributed populations with equal variances. ​ The 95% confidence interval for the difference between the two population means is (use rounded standard error)

In a sample of 40 Democrats, 6 opposed the President's foreign policy; while of 50 Republicans, 8 were opposed to his policy.Determine a 90% confidence interval estimate for the difference between the proportions of the opinions of the individuals in the two parties.

Salary information regarding male and female employees of a large company is shown below. ​ The point estimate of the difference between the means of the two populations is

The results of a recent poll on the preference of teenagers regarding the types of music they listen to are shown below. ​ The point estimate of the difference between the two population proportions is

In hypothesis tests about p₁ - p₂, the pooled estimator of p is a​(n)

The following information was obtained from matched samples taken from two populations.Assume the population of differences is normally distributed. ​ The null hypothesis tested is H₀: μd = 0.The test statistic for the difference between the two population means is

In order to estimate the difference between the average hourly wages of employees of two branches of a department store, the following data have been gathered. ​ A point estimate for the difference between the two population means is

The results of a recent poll on the preference of shoppers regarding two products are shown below. ​ The point estimate for the difference between the two population proportions in favor of this product is

A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics today and those enrolled five years ago.A sample of final examination scores from students enrolled today and from students enrolled five years ago was taken.You are given the following information. ​ The test statistic for the difference between the two population means is

An insurance company selected samples of clients under 18 years of age and over 18 and recorded the number of accidents they had in the previous year.The results are shown below. ​ We are interested in determining if the accident proportions differ between the two age groups. The pooled estimator of the population proportion is