Has the average cost of electricity increased? In the past, the population mean electricity cost was $245 per quarter with a population standard deviation of $40. A recent sample of 36 households had a mean of $285 per quarter. Assume the conditions are satisfied, and do NOT need to be checked here. a) Write the hypotheses to answer the question. b) SHOW BRIEF CALCULATIONS, for the calculated test statistic. c) Give the critical value, if using the 1% level of significance. d) Give your decision. e) Give your conclusion