A variable is normally distributed with mean 20 and standard deviation 8. Use your graphing calculator to find each of the following areas. Write your answers in decimal form. Round to the nearest thousandth as needed. a) Find the area to the left of 20. b) Find the area to the left of 15. c) Find the area to the right of 18. d) Find the area to the right of 25. e) Find the area between 15 and 28.