Given:
[tex]\begin{gathered} \mu=19.9 \\ \sigma=33.1 \\ n=40 \end{gathered}[/tex]
To Determine:
[tex]P(X>8.9)[/tex]
Solution
[tex]\begin{gathered} P(X>z) \\ z=\frac{x-\mu}{\sigma}=\frac{8.9-19.9}{33.1}=\frac{-11}{33.1}=-0.3323 \end{gathered}[/tex][tex]P(X>8.9)=1-P(X<8.9)=1-0.36982=0.63018[/tex]
Hence, P(x>8.9) = 0.6302 (nearest 4 d. p)
