Determine the total area under the standard normal curve in parts (a) through (c) below. (a) Find the area under the normal curve to the left of z= -1 plus the area under the normal curve to the right of z=1. The combined area is (Round to four decimal places as needed) (b) Find the area under the normal curve to the left of z= -1.56 plus the area under the normal curve to the right of z= 2.56 The combined area is (Round to four decimal places as needed) © Find the area under the normal curve to the left of z=-0.27 plus the area under the normal curve to the right of z=1.20 The combined area is (Round to four decimal places as needed)