For problems 4, 5, & 6 assume populations are normally distributed. 4) A sample size of 220 patients that got Covid revealed they had a sample mean incubation period of 5.1 days and the study used a population standard deviation of 2.0. Round all decimals to 3 places. 15 points a) Find the margin of error for a 90% confidence level. Show all work and values used. b) Find a 90% confidence interval. Show all work and values used. c) Interpret your results. d) Find the minimum sample size needed to have an error term within 1 point of the population mean at a 90 % confidence level. Show all work and values used