Answer:
17
Step-by-step explanation:
[tex]\displaystyle Z=\frac{\text{Observed Value}-\text{Mean of the Sample}}{\text{Standard Deviation of the Sample}}\\\\Z=\frac{x-\mu}{\sigma}\\ \\-1.5=\frac{x-23}{4}\\ \\-6=x-23\\\\17=x[/tex]
Therefore, the observed value that gives a z-score of -1.5 is 17
