One year ago, Joan was five times as old as her pony. In one year's time, the sum of the ages will be 22. How old is Joan now?
1 answer:
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Answer:
For this case the confidence interval is given by :
Step-by-step explanation:
Data provided
represent the sample mean for the fuel efficiencies
population mean
s=2.51 represent the sample standard deviation
n=601 represent the sample size
Confidence interval
The formula for the confidence interval of the true mean is given by:
(1)
The degrees of freedom for this case is given by:
The Confidence level for this case is 0.95 or 95%, and the significance level and
and the critical value is given by
Replcing into the formula for the confidence interval is given by:
For this case the confidence interval is given by :