how do you do longhand

18. Genetically Modified Organisms You wish to estimate, with 99% confidence, the population proportion of U.S. adults who support labeling legislation for genetically modified organisms (GMOs). Your estimate must be accurate within 2% of the population proportion. (a) No preliminary estimate is available. Find the minimum sample size needed. (b) Find the minimum sample size needed, using a prior survey that found that 75% of U.S. adults support labeling legislation for GMOs. (Source: The Harris Poll)