Answer :
The correct answer is:
c)75.4 to 94.6
Explanation:
The formula for a confidence interval is:
[tex] \mu \pm z*(\frac{\sigma}{\sqrt{n}}) [/tex],
where μ is the mean, z is the z-score associated with the level of confidence we want, σ is the standard deviation, and n is the sample size.
Our mean is 85, our standard deviation is 12, our sample size is 6, and since we want 95% confidence, our z-score is 1.96:
[tex] 85\pm 1.96(\frac{12}{\sqrt{6}})=85\pm 9.6=85-9.6, 85+9.6=75.4, 94.6 [/tex]