We will make use of the z-score to calculate the probability. The z-score is calculated using the formula:
[tex]z=\frac{x-\mu}{\sigma}[/tex]where x is the score, μ is the mean, and σ is the standard deviation.
From the question, we have the following parameters:
[tex]\begin{gathered} x=11.8 \\ \mu=8.4 \\ \sigma=1.4 \end{gathered}[/tex]Therefore, we have the z-score to be:
[tex]\begin{gathered} z=\frac{11.8-8.4}{1.4} \\ z=2.43 \end{gathered}[/tex]Using a calculator, we can get the probability value to be:
[tex]P=0.9925[/tex]The probability is 0.9925 or 99.25%.
