A confidence interval for a population mean is to be estimated. The population standard deviation  is guessed to be anywhere from 14 to 24. The half-width B desired could be anywhere from 2 to 7.

a. Tabulate the minimum sample size needed for the given ranges of σ and B.

b. If the fixed cost of sampling is $350 and the variable cost is $4 per sample, tabulate the sampling cost for the given ranges of  and B.

c. If the cost of estimation error is given by the formula 10B2, tabulate the total cost for the given ranges of σ and B. What is the value of B that minimizes the total cost when  = 14? What is the value of B that minimizes the total cost when σ = 24?