1.One class of 75 students has an average midterm score of 67 and anSD of 12. Another class of 325 students has an average of 72 and an SD of15. Find the average and the SD of the combined list of 400 students. Hint:This uses the SD of a long list formula.2. Find the average and SD of 1.2, 2.7, 3.1, 4.9, 5.3. Hint: Use the secondformula for SD.3. Find formulas for the average and SD of 1, 2, 3, · · · , n. Hint: Thinkabout 5) and 6) on the first page.