Question

 find P(-2.31 < Z ≤ 0.82).

Answer 1

$$P(-2.31<Z\leq0.82)=P(Z\leq 0.82)-P(Z\leq-2.31)$$

$$\approx0.7938919-0.0104441\approx0.783448$$

$$P(-2.31<Z\leq0.82)=0.783448$$