Activity: The Confidence Intervals Applet The Confidence Intervals applet at the book's Web site will quickly generate many confidence intervals. In this Activity, you will use the applet to investigate the idea of a confidence level. 1. Go http://digitalfirst.bfwpub.com/stats applet/stats applet 4 ci.html and launch the applet. Use the default set-tings: confidence level 95% and sample size n = 20. 2. Click "Sample" to choose an SRS and display the resulting confidence interval. Did the interval capture the population mean m (what the applet calls a "hit")? Do this a total of 10 times. How many of the intervals captured the population mean ? Note: So far, you have used the applet to take 10 SRSs, each of size n = 20. Be sure you understand the difference between sample size and the number of samples taken. 3. Reset the applet. Click "Sample 25" twice to choose 50 SRSs and display the confidence intervals based on those samples. How many captured the parameter u? Keep clicking "Sample 25" and observe the value of "Percent hit." What do you notice? 4. Repeat Step 3 using a 90% confidence level. 5. Repeat Step 3 using an 80% confidence level. 6. Summarize what you have learned about the relationship between confidence level and "Percent hit" after taking many samples. . Confidence Level (C): 95 Population Distribution - Sample Size (n): 20 SAMPLE SAMPLE 25 Hit: 23 Total: 25 Percent hit: 0.92 RESET