Sales ($ millions)	Number of entrepreneurs
0-1	2000
1-10	200
10-100	20

We want to estimate the average sales of a population of entrepreneurs. This population has been divided into 3 strata according to their prior sales. We want to select a sample size of 222. Assume a uniform distribution of sales within each stratum. (a) Estimate the average sales with a 95% confidence interval for a stratified design with proportional allocation. (b) Repeat (a) with an optimal stratified Neyman design.