Question

Question:Chapter 6, Section 4-D, Exercise 180

Use the formula to find the standard error of the distribution of differences in sample means, x¯1-x¯2.

Samples of size 120 from Population 1 with mean 90 and standard deviation 14 and samples of size 90 from Population 2 with mean 79 and standard deviation 15

Round your answer for the standard error to two decimal places.

standard error = Enter your answer in accordance to the question statement

the absolute tolerance is +/-0.01

Chapter 6, Section 4-D, Exercise 184

Use a t-distribution to answer this question. Assume the samples are random samples from distributions that are reasonably normally distributed, and that a t-statistic will be used for inference about the difference in sample means. State the degrees of freedom used.

Find the endpoints of the t-distribution with 2.5% beyond them in each tail if the samples have sizes n1=17 and n2=21.

Enter the exact answer for the degrees of freedom and round your answer for the endpoints to two decimal places.

degrees of freedom =

endpoints = ±

Chapter 6, Section 4-D, Exercise 186

Use a t-distribution to answer this question. Assume the samples are random samples from distributions that are reasonably normally distributed, and that a t-statistic will be used for inference about the difference in sample means. State the degrees of freedom used.

Find the proportion in a t-distribution less than -1.4 if the samples have sizes n1=30 and n2=40.

Enter the exact answer for the degrees of freedom and round your answer for the area to three decimal places.

degrees of freedom =

proportion =

Answer 1