Exam 10: Statistical Inferences Based on Two Samples

When we test H₀: μ₁ - μ₂ ≤ 0,H_A: μ₁ - μ₂> 0, ₁ = 15.4, ₂ = 14.5,σ₁ = 2,σ₂ = 2.28,n₁ = 35,and n₂ = 18 at α = .01,what is the value of the test statistic?

Find a 95 percent confidence interval for the difference between the proportions of people who prefer cola versus root beer (RB),where

Given the following information about a hypothesis test of the difference between two means based on independent random samples,which one of the following is the correct rejection region at a significance level of .05?

The controller of a chain of toy stores is interested in determining whether there is any difference in the weekly sales of store 1 and store 2.The weekly sales are normally distributed.This problem should be analyzed using an independent means method.

When comparing the variances of two normally distributed populations using independent random samples,if s₁² = s₂²,the calculated value of F will always be equal to one.

An experiment in which there is no relationship between the measurements on the different samples is a(n)______ experiment.

When we test H₀: μ₁ ≤ μ₂,H_A: μ₁> μ₂ at α = .10,where what is the estimated pooled variance?

A test of spelling ability is given to a random sample of 10 students before and after they complete a spelling course.The mean score before the course was 119.60 and after the course the mean score was 130.80.The standard deviation of the difference is 16.061.Test the hypothesis at α = .05 using a t test.

Find a 95 percent confidence interval for μ₁ - μ₂,where (Assume equal population variances. )

A marketing research company surveyed grocery shoppers on the East Coast and West Coast to find the percentage of the customers who prefer chicken to other meat.The data are given below. Is the proportion of customers who prefer chicken higher on the West Coast? Test at α = .05.

Suppose that a realtor is interested in comparing the price of midrange homes in two cities in a midwestern state.She conducts a small survey in the two cities,looking at the price of midrange homes.Assume equal population variances. Calculate the pooled estimate of σ² (rounded to nearest hundred).

The registrar at a state college is interested in determining whether there is a difference of more than one credit hour between male and female students in the average number of credit hours taken during a term.She selected a random sample of 60 male and 60 female students and observed the following sample information. Calculate the test statistic to be used in the analysis.Assume unequal variances.

Two hospital emergency rooms use different procedures for triage of their patients.We want to test the claim that the mean waiting time of patients is the same for both hospitals.The 40 randomly selected subjects from one hospital produce a mean of 18.3 minutes.The 50 randomly selected patients from the other hospital produce a mean of 25.31 minutes.Sample standard deviations are s_a = 2.1 minutes and s_b = 2.92 minutes.Set up the null hypothesis to determine whether there is a difference in the mean waiting time between the two hospitals.

If we are testing the hypothesis about the mean of a population of paired differences with samples of n₁ = 8,n₂ = 8,the degrees of freedom for the t statistic is ____.

Calculate the pooled variance where sample 1 has data: 16,14,19,18,19,20,15,18,17,18;and sample 2 has data: 13,19,14,17,21,14,15,10,13,15.

A test of spelling ability is given to a random sample of 10 students before and after they complete a spelling course.The mean score before the course was 119.60,and after the course the mean score was 130.80.The standard deviation of the difference is 16.061.Calculate a 99 percent confidence interval.

Two hospital emergency rooms use different procedures for triage of their patients.We want to test the claim that the mean waiting time of patients is the same for both hospitals.The 40 randomly selected subjects from one hospital produce a mean of 18.3 minutes.The 50 randomly selected patients from the other hospital produce a mean of 25.31 minutes.Assume s_a = 2.1 minutes and s_b = 2.92 minutes.What do you conclude about the waiting time for patients in the two hospitals,testing at α = .001?

What is the value of the computed F statistic for testing equality of population variances where s₁² = .004 and s₂² = .002? Consider H_A: σ₁²> σ₂².

The registrar at a state college is interested in determining whether there is a difference of more than one credit hour between male and female students in the average number of credit hours taken during a term.She selected a random sample of 60 male and 60 female students and observed the following sample information. Set up the alternative hypothesis to test the claim.