Homework Questions?. Section 9.3 Tests about a Population Mean

Homework Questions?

Section 9.3

Tests about a Population Mean

One Sample t Test

Find the p-value by calculating the probability of getting a t statistic this large or larger in the direction specified by the alternative hypothesis with

Computing the test statistic and p-value of AAA batteries from section 9.1 The battery company wants to test vs. based

on a SRS of 15 new AAA batteries with a mean lifetime of hours and standard deviation hours. What is the test statistic? (t)

Find the p-value.

Can we still make conclusions?

Two-Sided Tests What if you were performing a test of vs.

based on a sample of and obtained ?

Example – Health Streams The level of dissolved oxygen (DO) in a stream

or river is an important indicator of the water’s ability to support aquatic life. A researcher measures the DO level at 15 randomly chosen locations along a stream. Here are the results in mg/l:

A DO level below 5 mg/l puts aquatic life at risk.

4.53

5.04

3.29

5.23

4.13

5.50

4.83

4.40

5.42

6.38

4.01

4.66

2.87

5.73

5.55

XX

Healthy Streams Can we conclude that aquatic life in this

stream is at risk? Carry out a test at the significance level to help you answer the question.

State:

Plan:

Healthy Streams Do:

Conclude:

Healthy Streams Given your conclusion, which kind of mistake –

Type I or Type II error – could you have made? Explain what this would mean in context.

Again…look at a confidence interval… Look at 95% confidence interval… For means:

Paired Data - Flip to page 581 Matched Pairs! Only do (3, 4, 5)

Homework

Pg. 587 (63-69 odd, 70, 73-79 odd, 91, 95, 96, 99-104)