A population has standard deviation o = 17.6. Part 1 of 2 (a) How large a sample must be drawn so that an 80% confidence interval for u will have a margin of error equal to 4.3? Round the critical value to no less than three decimal places. Round the sample size up to the nearest integer. A sample size of is needed to be drawn in order to obtain an 80% confidence interval with a margin of error equal to 4.3