Answer:
Option c -2.8571
Step-by-step explanation:
z-score are calculated as
[tex]z=\frac{xbar-mean}{\frac{S.D}{\sqrt{n} } }[/tex].
We are given that mean=120 and standard deviation=S.D=35 as X~N(120,35).
Sample size=n=25.
We have to find z-score for x-bar=100. So,
z-score=[100-120]/[35/√25]
z-score=[-20]/[35/5]
z-score=-20/7
z-score=-2.8571.
Thus, the z-score associated with x-bar = 100 is -2.8571.
