1. The average weight of 40 randomly selected minivans is 4150 pounds. The standard deviation of all minivans is 480 pounds. Estimate the population average with 88% confidence. (6 marks) a) Briefly explain why the 2 distribution should be used for developing the confidence interval for the population average in this case. (1 mark) b) Estimate the true population average with 88% confidence. Check the requirement to validate the interval. Use Excel to find the critical value. (3 marks) c} Ifthe desired margin of error is 25 pounds, how large a sample is needed with 88% confidence? (2 marks)