E. Increasing the sample size would increase the probability of a Type I error.
Researchers wish to test how rangelands growth is affected by wildfire. A very large open area is
divided into 28 equally sized plots and subjected to a controlled burn. One year later, the
researchers calculate the percentage of grass returned in each plot after the fire damage. The
average percentage return for these 28 plots was 58.5% with a standard deviation of 6.5%. Which
of the following represents a 95% confidence interval to estimate the average proportion of grass
return one year after a fire?
A. 0.585 ± 1.96(0.065/
B. 0.585 ± 2.052(0.065/
C. 0.585 ± 2.052(0.065/
D. 0.585 ± 1.96(0.065/
E.
- Which of the following is NOT true of the χ^2 probability distribution function?
A. The area under the χ^2 curve is 1.
B. χ^2 is defined only for nonnegative values of the variable.
C. For small degrees of freedom, the curve displays strong right-skewness.
D. For the same α, as the number of degrees of freedom increases, the critical value for the
rejection region decreases.
E. χ^2 is actually a family of probability distributions defined by its degrees of freedom.
Tucson, Arizona, hosts the world’s largest gem and mineral show every February. A government
official claims that more than 50% of city residents have been to the Gem Show at least once. You
decide to test this theory, take a simple random sample of 200 Tucson residents, and discover that
108 have attended. Which of the following is the appropriate calculation of the test statistic for the
hypothesis proposed by the government official?
A.