Where:
[tex]\begin{gathered} X1=36 \\ X2=78 \\ \mu=82 \\ \sigma=4 \end{gathered}[/tex]So:
[tex]\begin{gathered} P(36\le X\le78)=P(\frac{78-82}{4}\le Z\le\frac{86-82}{4}) \\ P(36\le X\le78)=P(-1\le Z\le1) \\ P(36\le X\le78)=0.6827\approx0.68 \end{gathered}[/tex]As a percentage: 68%