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 0 3174 Round to four decimal places as needed b Find the area under the normal curve to the left of z 1 52 plus the area under the normal curve to the right o z 2 52 The combined area is Round to four decimal places as needed