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Chapter 9: Q.65 (page 587)

A retailer entered into an exclusive agreement with a supplier who guaranteed to provide all products at competitive prices. The retailer eventually began to purchase supplies from other vendors who offered better prices. The original supplier filed a lawsuit claiming violation of the agreement. In defense, the retailer had an audit performed on a random sample of 25 invoices. For each audited invoice, all purchases made from other suppliers were examined and compared with those offered by the original supplier. The percent of purchases on each invoice for which an alternative supplier offered a lower price than the original supplier was recorded.26 For example, a data value of 38 means that the price would be lower with a different supplier for 38% of the items on the invoice. A histogram and some computer output for these data are shown below. Explain why we should not carry out a one-sample t test in this setting.

Short Answer

Expert verified

we cannot carry out a one-sample t-test in this setting as the sample has been selected through simple random technique.

Step by step solution

01

Introduction

A test statistic is a statistic utilized in statistical hypothesis testing. A hypothesis test is typically specified as far as a test statistic, considered as a numerical synopsis of an informational collection that decreases the information to one worth that can be utilized to play out the hypothesis test.

02

Explanation

The assumption of normality is not fulfilled as the sample size = 20which is less than30.

Sample selection has been done through a simple random technique.

Hence we cannot carry out a one-sample t-test in this setting as the sample has been selected through a simple random technique and the sample size is 20which is less than 30hence the normality assumption is not satisfied.

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Most popular questions from this chapter

Cash to find work? (5.2) Will cash bonuses speed the return to work of unemployed people? The Illinois Department of Employment Security designed an experiment to find out. The subjects were 10,065 people aged 20 to 54 who were filing claims for

unemployment insurance. Some were offered \(500 if they found a job within 11 weeks and held it for at least 4 months. Others could tell potential employers that the state would pay the employer \)500 for hiring them. A control group got neither kind of bonus.

(a) Describe a completely randomized design for this experiment.

(b) How will you label the subjects for random assignment? Use Table D at line 127 to choose the first 3 subjects for the first treatment.

(c) Explain the purpose of a control group in this setting.

Study more! A student group claims that first-year students at a university study 2.5hours per night during the school week. A skeptic suspects that they study less than that on average. He takes a random sample of 30first-year students and finds that x=137minutes and sx=45minutes. A graph of the data shows no outliers but some skewness. Carry out an appropriate significance test at the 5%significance level. What conclusion do you draw?

After checking that conditions are met, you perform a significance test of H0:μ=1versus Hα:μ≠1. You obtain a Pvalue of 0.022. Which of the following is true?

(a) A95%confidence interval for μwill include the value 1

(b) A 95%confidence interval forμwill include the value 0.

(c) A99% confidence interval forμwill include the value 1

(d) A 99%confidence interval for μwill include the value 0

(e) None of these is necessarily true.

Stating hypotheses State the appropriate null and alternative hypotheses in each of the following cases.

(a) The average height of 18-year-old American women is 64.2inches. You wonder whether the mean height of this year's female graduates from a large local high school (over 3000students) differs from the national average. You measure an SRS of 48female graduates and find that X=63.1inches.

(b) Mr. Starnes believes that less than 75%of the students at his school completed their math homework last night. The math teachers inspect the homework assignments from a random sample of students at the school to help Mr. Starnes test his claim.

- Check conditions for carrying out a test about a population proportion or mean.

- Interpret P-values in context.

Haemoglobin is a protein in red blood cells that carries oxygen from the lungs to body tissues. People with less than 12 grams of haemoglobin per deciliter of blood (g/dl) are anaemic. A public health official in Jordan suspects that Jordanian children are at risk of anaemia. He measures a random sample of 50 children.
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