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Chapter 10: Q 17. (page 641)

Shrubs and fire Fire is a serious threat to shrubs in dry climates. Some shrubs can

resprout from their roots after their tops are destroyed. Researchers wondered if fire would help with resprouting. One study of resprouting took place in a dry area of Mexico. The researchers randomly assigned shrubs to treatment and control groups. They clipped the tops of all the shrubs. They then applied a propane torch to the stumps of the treatment group to simulate a fire. All 12of the shrubs in the treatment group resprouted. Only 8of the 12shrubs in the control group resprouted.

a. State appropriate hypotheses for performing a significance test. Be sure to define the parameters of interest.

b. Check if the conditions for performing the test are met.

Short Answer

Expert verified

a. The hypothesis are H0:p1=p2and Ha:p1>p2

b. All conditions are not met.

Step by step solution

01

Given Information

It is given that the researchers want to know that if there is a difference in the proportion of shrubs that received the treatment and resprouted and the shrubs that did not received the treatment and resprouted.

x1=12

x2=8

n1=12

n2=12

02

Appropriate hypothesis

Claim is that proportion is greater than shrubs in treatment group.

The appropriate hypothesis is:

Null: H0:p1=p2

Alternative: Ha:p1>p2

p1is proportion of shrubs that received the treatment and resprouted.

p2is proportion of shrubs that did not received the treatment and resprouted.

03

Conditions

Three conditions are:

Random: Independent random samples assigned to shrubs.

Independent: 12shrubs is less than 10%of all shrubs.

Normal: There are 12success and zero failures, zero is less than ten.

All conditions are not satisfied. We cannot use hypothesis for testing a claim.

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Have a ball! Can students throw a baseball farther than a softball? To find out, researchers conducted a study involving 24randomly selected students from a large high school. After warming up, each student threw a baseball as far as he or she could and threw a softball as far as he she could, in a random order. The distance in yards for each throw was recorded. Here are the data, along with the difference (Baseball 鈥� Softball) in distance thrown, for each student:

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