A population consists of two strata, H and L, of sizes 100,000 and 500,000 and standard deviations 20 and 12, respectively. A stratified sample of size 100 is to be taken.

a. Find the optimal allocation for estimating the population mean.

b. Find the optimal allocation for estimating the difference of the means of the strata,

mu_H - mu_L

Thank you!