Answer:
If x=0 then the answer is 20.
Step-by-step explanation:
Answer: -1.33 .
Step-by-step explanation:
Formula to find the Z-score :

Given: Mean = 191 and Standard deviation = 21
Then , the z-score corresponding to the expected value of 163 will be :

Hence, the z score corresponding to selling 163 inhalers is -1.33 .