I need help with this question ( it is from Elementary survey sampling

Reed and Chagnon (1987) wanted to estimate the number of greater snow geese on Bylot Island, in Canada's Northwest Territories (the island is an important breeding ground for the bird). They gridded the island into 400 2 x 2 km plots (excluding areas that were patently not usable by geese). They divided 400 plots into three strata (high, medium, and low quality), based on ecological factors that are known to be associated with goose abundance. The statistics are summarized in the below table: Stratum Stratum size Sample size Mean Sample standard deviation s High quality 65 34 412.5 316.9 Medium quality 127 28 136.8 127.7 Low quality 208 21 16.2 30.5 (a) Estimate the mean number of geese per 2 x 2 km plot, and place an error bound on the estimation. (b) Estimate the total number of geese on Bylot Island, and place an error bound on the estimation. (c) Using the information above, find the sample sizes from each stratum to obtain a bound on the error of estimation equal to 5000. Use proportional allocation. (ai = M