Chapter 9, Problem 15P

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8th Edition

Frederick J Gravetter + 1 other

ISBN: 9781133956570

Textbook Problem

For several years researchers have noticed that there appears to be a regular, year-by-year increase in the average IQ for the general population. This phenomenon is called the Flynn effect after the researcher who first reported it (Flynn. 1984, 1999), and it means that psychologists must continuously update IQ tests to keep the population mean at
*n* = 64 of today's 20-year-old adults. The average score for the sample was *M =* 107 with a standard deviation of *s* = 12.

a. Based on the sample, is the average IQ for today's population significantly different from the average 10 years ago, when the test would have produced a mean of

b. Make an 80% confidence interval estimate of today’s population mean IQ for the 10-year-old test.

**a.**

To determine

**To state:** The decision of hypothesis test performed for the given question using two-tailed test.

Explanation

**Given info:**

The data states that sample size is 64 with the population mean, sample mean, and standard deviation is 100, 107 and 12.

**Calculations:**

The test hypotheses are:

Null Hypothesis is

Alternative Hypothesis is

*Degrees of Freedom:*

The critical value is obtained from the t-table for

The estimated standard error s_{m}:

The t-statistic is obtained as:

Substitute 107 for

**b.**

To determine

**To make:** A 80% confidence interval estimate for the given question

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