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Happy customers As the Hispanic population in the United States has grown, businesses have tried to understand what Hispanics like. One study interviewed separate random samples of Hispanic and Anglo customers leaving a bank. Customers were classified as Hispanic if they preferred to be interviewed in Spanish or as Anglo if they preferred English. Each customer rated the importance of several aspects of bank service on a 10- point scale.25 Here are summary results for the importance of “reliability” (the accuracy of account records, etc.):

Researchers want to know if there is a difference in the mean reliability ratings of all Anglo and Hispanic bank customers.

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

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

Short Answer

Expert verified

Part a) The hypothesis is:

H0:μ1=μ2Ha:μ1notequaltoμ2

Part b) All conditions are met.

Step by step solution

01

Part a) Step 1: Given information

The given claim that a difference in the means.

02

Part a) Step 2: Explanation

We must now determine the appropriate hypotheses for performing a significance test.

As a result, the claim represents either the null hypothesis or the alternative hypothesis. According to the null hypothesis, the population proportions are equal. If the claim is the null hypothesis, then the alternative hypothesis states the inverse of the null hypothesis.

Therefore, the following are the appropriate hypotheses:

H0:μ1=μ2Ha:μ1notequaltoμ2

Where we have,

The true mean reliability rating of all Angle bank customers is μ1

μ2=represents the true mean reliability rating of all Hispanic bank customers.

03

Part b) Step 1: Explanation

There are three requirements that must be met:

It is satisfying because the samples are drawn at random from different populations.

Independent: It is satisfying because the sample of 92Anglo customers is less than 10%of the total Anglo customer population, and the sample of 86 Hispanic customers is less than 10%of the total Hispanic customer population.

Normal: It is satisfying because both samples are large, with sample sizes of at least 30.

As a result, all of the conditions are met, and a hypothesis test for the mean difference is appropriate.

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Most popular questions from this chapter

In an experiment to learn whether substance M can help restore memory, the brains of 20rats were treated to damage their memories. First, the rats were trained to run a maze. After a day, 10rats (determined at random) were given substance M and 7of them succeeded in the maze. Only 2of the 10control rats were successful. The two-sample z test for the difference in the true proportions

a. gives z=2.25,P<0.02 .

b. gives z=2.60,P<0.005 .

c. gives z=2.25,P<0.04 but not<0.02

d. should not be used because the Random condition is violated.

e. should not be used because the Large Counts condition is violated.

“I can’t get through my day without coffee” is a common statement from many college students. They assume that the benefits of coffee include staying awake during lectures and remaining more alert during exams and tests. Students in a statistics class designed an experiment to measure memory retention with and without drinking a cup of coffee 1 hour before a test. This experiment took place on two different days in the same week (Monday and Wednesday). Ten students were used. Each student received no coffee or one cup of coffee 1 hour before the test on a particular day. The test consisted of a series of words flashed on a screen, after which the student had to write down as many of the words as possible. On the other day, each student received a different amount of coffee (none or one cup).

a. One of the researchers suggested that all the subjects in the experiment drink no coffee before Monday’s test and one cup of coffee before Wednesday’s test. Explain to the researcher why this is a bad idea and suggest a better method of deciding when each subject receives the two treatments.

b. The researchers actually used the better method of deciding when each subject receives the two treatments that you identified in part (a). For each subject, the number of words recalled when drinking no coffee and when drinking one cup of coffee is recorded in the table. Carry out an appropriate test to determine whether there is convincing evidence that drinking coffee improves memory, on average, for students like the ones in this study.

Literacy A researcher reports that 80%of high school graduates, but only 40%of high school dropouts, would pass a basic literacy test. Assume that the researcher’s claim is true. Suppose we give a basic literacy test to a random sample of 60high school graduates and a separate random sample of 75high school dropouts.p^G,p^Dbe the sample proportions of graduates and dropouts, respectively, who pass the test.

a. What is the shape of the sampling distribution of p^G-p^D. Why?

b. Find the mean of the sampling distribution.

c. Calculate and interpret the standard deviation of the sampling distribution.

Which of the following statements is false?

a. A measure of center alone does not completely summarize a distribution of quantitative data.

b. If the original measurements are in inches, converting them to centimeters will not change the mean or standard deviation.

c. One of the disadvantages of a histogram is that it doesn’t show each data value.

d. In a quantitative data set, adding a new data value equal to the mean will decrease the standard deviation.

e. If a distribution of quantitative data is strongly skewed, the median and interquartile range should be reported rather than the mean and standard deviation.

Flight times The pilot suspects that the Dubai-to-Doha outbound flight typically takes longer. If so, the difference (Outbound−Return) in flight times will be positive on more days than it is negative. What if either flight is equally likely to take longer? Then we can model the outcome on a randomly selected day with a coin toss. Heads means the Dubai-to-Doha outbound flight lasts longer; tails means the Doha-to-Dubai return flight lasts longer. To imitate a random sample of 12days, imagine tossing a fair coin 12times.

a. Find the probability of getting 11or more heads in 12tosses of a fair coin.

b. The outbound flight took longer on 11of the 12days. Based on your result in part (a), what conclusion would you make about the Emirates pilot’s suspicion?

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