Aresearcher wishes to estimate, with % confidence, the population proportion of adults who think congress is doing a good or excellent job. her estimate must be accurate within 44% 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 % 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? nequals=nothing (round up to the nearest whole number as needed.)