Using the normal distribution, it is found that the z-scores are [tex]Z = \pm 1.227[/tex].
In a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the z-score of a measure X is given by:
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
The normal distribution is symmetric, which means that the middle 78% is between the 11th and the 89th percentile. Looking at the z-table, the z-scores are [tex]Z = \pm 1.227[/tex].
More can be learned about the normal distribution at https://brainly.com/question/24663213