Skillbuilder Applet Exercise demonstrates the effect that the level of confidence (1 )

has on the width of a confidence interval. Consider sampling from a population where 300 and 80.

a. Set the slider for level of confidence to 68%.
Click “sample!” to construct one 68% confidence interval. Note the upper and lower confidence limits and calculate the width of the interval.
Using “animate!” construct many samples and note the percent of intervals containing the true mean of 300. Click “stop” and “reset.”

b. Set the slider for level of confidence to 95%.
Click “sample!” to construct one 95% confidence interval. Note the upper and lower confidence limits and calculate the width of the interval.
Using “animate!” construct many samples and note the percent of intervals containing the true mean of 300. Click “stop” and “reset.”

c. Set the slider for level of confidence to 99%.
Click “sample!” to construct one 99% confidence interval. Note the upper and lower confidence limits and calculate the width of the interval.
Using “animate!” construct many samples and note the percent of intervals containing the true mean of 300. Click “stop.”

d. Using the information collected in parts a–c, what effect does the level of confidence have on the width of the interval. Why is this happening?

2882 3145 301.4 2601 280 300 320 340 sample! animate reset Confidence level (%) 90