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Chapter 9: Q.3 (page 546)

The Survey of Study Habits and Attitudes (SSHA) is a psychological test that measures

students’ attitudes toward school and study habits. Scores range from 0 to 200. The mean score for U.S. college students is about 115. A teacher suspects that older students have better attitudes toward school. She gives the SSHA to an SRS of 45

of the over 1000 students at her college who are at least 30 years of age.

Short Answer

Expert verified

Population mean for the student is115as per null hypothesis and it is more than115as per alternative hypothesis.

Step by step solution

01

introduction

Given,

Scores range from 0-200.

The mean score for U.S. college students is about115.

Calculating the null and alternative hypotheses.

02

explanation

The mean score for U.S. college students is115

Mean population value is115as per the null hypotheses

⇒H0:μ=115

Mean population value is greater than 115as per the alternative hypotheses

⇒Ha:μ>115

The population mean for the student is 115 as per null hypothesis and it is more than115 as per alternative hypothesis.

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Most popular questions from this chapter

Your company markets a computerized device for detecting high blood pressure. The device measures an individual’s blood pressure once per hour at a randomly selected time throughout a 12-hour period. Then it calculates the mean systolic (top number) pressure for the sample of measurements. Based on the sample results, the device determines whether there is significant evidence that the individual’s actual mean systolic pressure is greater than 130. If so, it recommends that the person seek medical attention.

(a) State appropriate null and alternative hypotheses in this setting. Be sure to define your parameter.

(b) Describe a Type I and a Type II error, and explain the consequences of each.

(c) The blood pressure device can be adjusted to decrease one error probability at the cost of an increase in the other error probability. Which error probability would you choose to make smaller, and why?

Heat through the glass How well materials conduct heat matters when designing houses, for example. Conductivity is measured in terms of watts of heat power transmitted per square meter of surface per degree Celsius of temperature difference on the two sides of the material. In these units, glass has conductivity about 1. The National Institute of Standards and Technology provides exact data on properties of materials. Here are measurements of the heat conductivity of 11randomly selected pieces of a particular type of glass:

1.111.071.111.071.121.081.081.181.181.181.12

Is there convincing evidence that the conductivity of this type of glass is greater than 1? Carry out a test to help you answer this question.

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Taking stock An investor with a stock portfolio worth several hundred thousand dollars sued his broker due to the low returns he got from the portfolio at a time when the stock market did well overall. The investor’s lawyer wants to compare the broker’s performance against the market as a whole. He collects data on the broker’s returns for a random sample of36weeks. Over the 10-year period that the broker has managed portfolios, stocks in the Standard & Poor’s 500index gained an average of 0.95%per month. The Minitab output below displays descriptive statistics for these data, along

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One-sided test Suppose you carry out a significance test of H0:μ=5versus Ha:μ>5based on a sample of size n=20and obtain t=1.81.

(a) Find the P-value for this test using (i) Table Band (ii) your calculator. What conclusion would you draw at the 5%significance level? At the 1%significance level?

(b) Redo part (a) using an alternative hypothesis ofHa:μ≠5.
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