Consider that:
P(-1.28 < z < 0.8) = P(z < 0.8) - P(z < -1.28)
By using a normal distribution table for z-scores, you have:
The first table give us the probability P(z<-1.28) = 0.10027 and the seconf table give us the probability P(z < 0.8) = 0.78814
By replacing the previous values into the expression for P(-1.28 < z < 0.8), you obtain:
P(-1.28 < z < 0.8) = 0.78814 - 0.10027 = 0.68787
Hence, the result is 0.68787
