20. Construct the indicated confidence interval for the difference between two population means. Assume that the two samples are independent simple random samples selected from normally distributed populations. Do not assume that the population standard deviations are equal. A baker wished to compare the baking times of two different types of pastries. Independent simple random samples of 25 brownies and 28 croissants were observed. The baking times, in minutes, were recorded, and the summary statistics are below. Construct a 90% confidence interval for - , the difference between the mean baking time for croissants and the mean baking time for brownies. Brownies x = 29 mins Croissants x2 = 20 mins S = 1.2 mins S = 1.7 mins n = 25 - 2 < 19.8 a. 1.8 b. 9.5 - 1 2