1)

Use at

-distribution to answer this question. Assume the samples are random samples from distributions that are reasonably normally distributed, and that at

-statistic will be used for inference about the difference in sample means. State the degrees of freedom used.

Find the proportion in at

-distribution less than-1.4

if the samples have sizesn1=30

andn2=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=

2)

Use at

-distribution to answer this question. Assume the samples are random samples from distributions that are reasonably normally distributed, and that at

-statistic will be used for inference about the difference in sample means. State the degrees of freedom used.

Find the endpoints of thet

-distribution with2.5%

beyond them in each tail if the samples have sizesn1=14

andn2=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=

3)

Use the formula to find the standard error of the distribution of differences in sample means,x1-x2

.

Samples of size115

from Population1

with mean85

and standard deviation13

and samples of size85

from Population2

with mean75

and standard deviation17

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

standard error=

Enter your answer in accordance to the question statement