Answer:
Step-by-step explanation:
A table of the normal distribution will tell you the area between z=0 and z=1 is about 0.34134. The distribution is symmetrical, so there is an equal area between z=-1 and z=0. The total area between z=-1 and z=1 is ...
2×0.34134 = 0.68268 ≈ 0.6827 = 68.27%