Question: a. Most Americans love participating in or at least watching sporting events. Some feel that sports have more that just entertainment value. In a survey of 1000 adults, conducted by KRC Research & Consulting, 78% felt that spectator sports have a positive effect on society. Find a 95% confidence interval for the percentage of the public that feel that sports have a positive effect on society.

b. For a comparison of the rates of defectives produced by two assembly lines, independent random samples of 100 items were selected from each line. Line A yielded 18 defectives in the sample, and line B yielded 12 defectives. Find a 98% confidence interval for the true difference in proportions of defectives for the two lines.