2. A sample of 15 newborn boys had a mean weight of 8.16 pounds. A sample of 20 newborn girls had a mean weight of 7.82 pounds. Assume that weights of newborn boys are normally distributed with standard deviation 0.90 pounds. Likewise, assume that weights of newborn girls are normally distributed with standard deviation 1.01 pounds. Let u be the true mean weight of a newborn boy and 2 be the true mean weight of a newborn girl. (a) (3 points) What is the margin of error, E, of a 90% confidence interval for 1-2? Round your answer to 2 decimal places. (b) (1 point) Construct a 90% confidence interval for - 2.