Answer:

Step-by-step explanation:
Given

-- City C
--- City K
Required
Determine the 90% confidence interval
This is calculated using:

Calculating 




For a 90% confidence level, the z-score is 1.65. So:

Calculating the standard deviation 

So:


So:


Answer:
Runners that decrease times are not improving
Step-by-step explanation:
Answer:
x^2+3x-18
Step-by-step explanation: hoped I helped
Step-by-step explanation:
90.......................