E Homework: Section 6.3 Confidence Intervals for Question 13, 6.3.17-T HW Score: 40.74%, 11 of 27 points Population Pr Part 1 of 3 O Points: 0 of 1 A researcher wishes to estimate, with 95% confidence, the population proportion of adults who think Congress is doing a good or excellent job. Her estimate must be accurate within 5% of the true proportion. (a) No preliminary estimate is available. Find the minimum sample size needed. (b) Find the minimum sample size needed, using a prior study that found that 18% of the respondents said they think Congress is doing a good or excellent job. (c) Compare the results from parts (a) and (b). (a) What is the minimum sample size needed assuming that no prior information is available? n= (Round up to the nearest whole number as needed.)