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Chapter 10: Q. 15 (page 668)

Mrs. Woods and Mrs. Bryan are avid vegetable gardeners. They use different fertilizers, and each claims that hers is the best fertilizer to use when growing tomatoes. Both agree to do a study using the weight of their tomatoes as the response variable. They had each planted the same varieties of tomatoes on the same day and fertilized the plants on the same schedule throughout the growing season. At harvest time, they each randomly select 15tomatoes from their respective gardens and weigh them. After performing a two-sample t-test on the difference in mean weights of tomatoes, they get t=5.24and P=0.0008. Can the gardener with the larger mean claim that her fertilizer caused her tomatoes to be heavier?

(a) No, because the soil conditions in the two gardens is a potential confounding variable.

(b) No, because there was no replication.

(c) Yes, because a different fertilizer was used on each garden.

(d) Yes, because random samples were taken from each garden.

Short Answer

Expert verified

The gardener with the larger mean can not claim that her fertilizer caused her tomatoes to be heavier (a) No because the soil conditions in the two gardens are a potential confounding variable.

Step by step solution

01

Given Information

We are given that At harvest time, they each randomly select 15 tomatoes from their respective gardens and weigh them. After performing a two-sample t-test on the difference in mean weights of tomatoes, they get t=5.24and P=0.0008

02

Explanation

According to question for comparison , all factors must be same. whether the p-value is less than alpha. maybe, condition of one soil patch will be better than other soil patch.

P-value less than alpha means that there is some association.

Therefore, the gardener with the larger mean can not claim that her fertilizer caused her tomatoes to be heavier . because the soil condition in two gardens is a potential confounding variable.

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Most popular questions from this chapter

The distribution of grade point averages for a certain college is approximately Normal with a mean of 2.5and a standard deviation of 0.6. According to the 68鈥�95鈥�99.7rule, within which interval would we expect to find approximately 81.5%of all GPAs for students at this college?

(a)(0.7,3.1)

(b)(1.3,3.7)

(c)role="math" localid="1650374007246" (1.9,3.7)

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Pat wants to compare the cost of one- and two-bedroom apartments in the area of her college campus. She collects data for a random sample of 10 advertisements of each type. The table below shows the rents (in dollars per month) for the selected apartments.

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Holly carried out the significance test shown below to answer this question. Unfortunately, she made some mistakes along the way. Identify as many mistakes as you can, and tell how to correct each one.

State: I want to perform a test of

H0:p1=p2

Ha:p1鈮�p2

at the 95%confidence level.

Plan: If conditions are met, I鈥檒l do a one-sample ztest for comparing two proportions.

  • Random The data came from a random sample of 385 black, never-married students.
  • Normal One student鈥檚 answer to the question should have no relationship to another student鈥檚 answer.
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Do: From the data, p^1=91149=0.61and p^2=117236=0.46.

Test statistic

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p=value From Table A, role="math" localid="1650292307192" P(z鈮�2.91)鈮�1-0.3982鈮�0.0018.

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