Answer all questions with explanation

1. Suppose that a population of 540 elementary units is divided into 3 strata and the samples selected from the strata are presented in the table below. " Estimate the mean of the population. Estimate the variance of the estimator. Find a 95 9'6 confidence interval about the mean. By considering all of them as a simple random sample, estimate the standard error. Compare the variance from the stratified sampling with the variance from the simple random sample and comment on your answers