A population was divided into three strata with N1 = 300, with N2 = 600, and with N3 = 500. From a past survey, the following estimates for the standard deviations in the three strata are available: s1 = 150, s2 = 75, s3 = 100.
a. Suppose an estimate of the population mean with a bound on the error of estimate of B = 20 is required. How large must the sample be? How many elements should be allocated to each stratum?
b. Suppose a bound of B = 10 is desired. How large must the sample be? How many elements should be allocated to each stratum?
c. Suppose an estimate of the population total with a bound of B = 15,000 is requested. How large must the sample be? How many elements should be allocated to each stratum?