PLEASE HELP! I need help with all the questions

You may need to use the appropriate appendix table or technology to answer this question. Suppose the CPA Practice Advisor reports that the mean preparation fee for 2017 federal income tax returns was $273. Use this price as the population mean and assume the population standard deviation of preparation fees is $100. (a) What is the probability that the mean price for a sample of 20 federal income tax returns is within $16 of the population mean? (Round your answer to four decimal places.) (b) What is the probability that the mean price for a sample of 70 federal income tax returns is within $16 of the population mean? (Round your answer to four decimal places.) (c) What is the probability that the mean price for a sample of 81 federal income tax returns is within $16 of the population mean?(Round your answer to four decimal places.) (d) Which, if any, of the sample sizes in parts (a), (b), and (c) would you recommend to ensure at least a 0.95 probability that the sample mean is within $16 of the population mean? (Select all that apply.) O 20 customers O 70 customers O 81 customers O none of the above