given Finding the Margin of Error In Exercises 35 and 36, use the confidence interval to find the estimated margin of error. Then find the sample mean. 35. Seedlings A biologist reports a confidence interval of (2.1, 3.5) when estimating the mean height (in centimeters) of a sample of seedlings. 36. Book Prices A store manager reports a confidence interval of (44.07, 80.97) when estimating the mean price (in dollars) of a sample of textbooks. SECTION 6.1 CONFIDENCE INTERVALS FOR THE MEAN (LARGE SAMPLES) 319 rod 41. Repair Costs: Washing Machines You work for a consumer advocate agency and want to find the mean repair cost of a washing machine. As part of your study, you randomly select 40 repair costs and find the mean to be $120.00. The sample standard deviation is $17.50. Construct a 95% confidence interval for the population mean repair cost. (Adapted from Consumer Reports) 42. Repair Costs: Refrigerators In a random sample of 60 refrigerators, the mean repair cost was $150.00 and the standard deviation was $15.50. Construct a 99% confidence interval for the population mean repair cost. (Adapted from Consumer Reports)