Answer: -1.33 .
Step-by-step explanation:
Formula to find the Z-score :
[tex]Z=\dfrac{\text{Expected value - Mean}}{\text{Standard deviation}}[/tex]
Given: Mean = 191 and Standard deviation = 21
Then , the z-score corresponding to the expected value of 163 will be :
[tex]Z=\dfrac{163-191}{21}\\\\=\dfrac{-28}{21}\approx-1.33[/tex]
Hence, the z score corresponding to selling 163 inhalers is -1.33 .