Chapter 11: Problem 11
How is the expected frequency of a category calculated for a goodness-of-fit test? What are the degrees of freedom for such a test?
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Chapter 11: Problem 11
How is the expected frequency of a category calculated for a goodness-of-fit test? What are the degrees of freedom for such a test?
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Determine the value of \(\chi^{2}\) for 14 degrees of freedom and an area of \(.10\) in the left tail of the chisquare distribution curve.
A drug company is interested in investigating whether the color of their packaging has any impact on sales. To test this, they used five different colors (blue, green, orange, red, and yellow) for the boxes of an over-the- counter pain reliever, instead of their traditional white box. The following table shows the number of boxes of each color sold during the first month. $$ \begin{array}{l|ccccc} \hline \text { Box color } & \text { Blue } & \text { Green } & \text { Orange } & \text { Red } & \text { Yellow } \\ \hline \text { Number of boxes sold } & 310 & 292 & 280 & 216 & 296 \\ \hline \end{array} $$ Using a \(1 \%\) significance level, test the null hypothesis that the number of boxes sold of each of these five colors. is the same.
Explain the difference between the observed and expected frequencies for a goodness-of-fit test.
An auto manufacturing company wants to estimate the variance of miles per gallon for its auto model AST727. A random sample of 22 cars of this model showed that the variance of miles per gallon for these cars is .62. Assume that the miles per gallon for all such cars are (approximately) normally distributed. a. Construct the \(95 \%\) confidence intervals for the population variance and standard deviation. b. Test at a \(1 \%\) significance level whether the sample result indicates that the population variance is different from \(.30\).
A sample of certain observations selected from a normally distributed population produced a sample variance of 46 . Construct a \(95 \%\) confidence interval for \(\sigma^{2}\) for each of the following cases and comment on what happens to the confidence interval of \(\sigma^{2}\) when the sample size increases. a. \(n=12\) b. \(n=16\) c. \(n=25\)
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