(Give your answers correct to TWO (2) decimal places) In a butter cookies packing plant, the weight (in grams) of a pack of butter cookies packed is normally distributed. A random sample of 10 packs was drawn from the plant, and their weights were measured with the following results. 19.5 19.5 20.2 19.7 20.2 19.8 20.2 19.6 20.0 19.9 (a) Calculate the unbiased estimate for the population mean u and the population standard deviation a of the weight (in grams) of all butter cookies packed in the plant. Answer: the unbiased estimate for His 19.86 grams, and the unbiased estimate for o is grams. (b) Find the 99% confidence interval for the population mean weight of butter cookies packed in the plant. Answer: the 9% confidence interval for the population mean weight of butter cookies packed in the plant is from grams to grams