According to a recent survey, the average earnings in a certain city were $42,700 in Educational Services and $79,500 in the Financial Services industry a) Suppose the standard deviation of earnings in Educational Services for the whole of the city was $13,900 and we want the standard deviation of average eamings in our survey to be $1200. What sample size do we need to take? b) Suppose we used a-sample of size 310 for our estimate of average earnings in Financial Services and the standard deviation of earnings in our survey was $19,800. What is the standard error of the average earnings in Financial Services? a) The sample size needed is (Round up to the nearest whole number.)