Answer
Answer = 0.9926
Work Step by Step
Want to find P(-2.68 < z < 2.68)
1) Find the area of everything outside the desired region:
P( z < -2.68) + P( z > 2.68)
= 0.0037 + (1- 0.9963)
= 0.0074
2) Remember that the area under the normal curve is equal to 1. Hence:
P( -2.68 < z < 2.68) = 1 - 0.0074 = 0.9926