In recent years the mean number of miles driven per year by residents of a particular state was 11,568. A researcher wishes to t
2 answers:
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Answer:
So on this case the 95% confidence interval would be given by (12.150;16.690)
Step-by-step explanation:
Previous concepts
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
represent the sample mean
population mean (variable of interest)
represent the population standard deviation
n=36 represent the sample size
Solution to the problem
The confidence interval for the mean is given by the following formula:
(1)
Since the Confidence is 0.95 or 95%, the value of and
, and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.025,0,1)".And we see that
Now we have everything in order to replace into formula (1):
So on this case the 95% confidence interval would be given by (12.150;16.690)
Answer:
6 dm
Step-by-step explanation:
Triangle DBE is similar to triangle ABC, so their side lengths are proportional.
DE/AC = DB/AB
The length of DB can be found from ...
DB +AD = AB
DB = AB -AD = (15 -10) dm = 5 dm
So, we can fill in the proportion:
DE/(18 dm) = (5 dm)/(15 dm)
DE = (18 dm)·(1/3) . . . . . . . . . . simplify, multiply by 18 dm
DE = 6 dm
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It can be helpful to draw and label a figure.
