Answer:
95% confidence level should be used for a confidence​ interval.
The given confidence interval contains the value of 85 ​sec, so there is not sufficient evidence to support the claim that the mean is greater than 85 sec.
Step-by-step explanation:
0.05 significance level
1 - 0.05 = 0.95
0.95*100% = 95%
This means that a 95% confidence level should be used for a confidence​ interval.
Confidence interval is found to be −1.8 sec<μ<213.5 ​sec, what should we conclude about the​ claim?
Contains the value of 85 sec, thus there is not sufficient evidence to support the claim that the mean is greater than 85 sec.