Answer: C. 
Step-by-step explanation:
The confidence interval for difference of two population mean is given by :-

Given : Level of significance : 
Then , significance level : 
Critical value : 


Hence, a 99% confidence interval for the difference between the mean wait times of everyone who rode both rides 
60$. These are my equations :
600 * 0.2 = 120 ; 600 - 120 = 480
Then...
600 * 0.1 = 60 ; 600 - 60 = 540
Which then became....
540 - 480 = 60
Answer:
-1/-6
Step-by-step explanation:
1/6 is equivalent to-1/-6