please explain your answer well and the formulas you use

41. A civil engineer wishes to measure the compressive strength of two different types of concrete. A random sample of 10 specimens of the first type yielded the following data (in psi) Type 1: 3,250, 3,268, 4,302, 3,184, 3.266 3,297, 3,332, 3,502, 3,064, 3.116 whereas a sample of 10 specimens of the second yielded the data Type 2: 3,094, 3.106, 3.004, 3,066, 2,984, 3,124, 3,316, 3,212, 3,380, 3,018 If we assume that the samples are normal with a common variance, determine (a) a 95 percent two-sided confidence interval for ?1-112, the difference in (b) a 95 percent one-sided upper confidence interval for 1 2 means; (c) a 95 percent one-sided lower confidence interval for ? 1-12