Of the 12 available months, of them end in the letter "r" (Sep, Oct, Nov, Dec). The sample space consists of all 12 possible choices of 1 month, but the only outcome we care about is any 1 of these 4 being selected. The probability of choosing any one of these is
. How you describe the probability is up to interpretation, but probably a good convention to use is to say that an event is "unlikely" to happen if that event has a probability less than 0.5 of occurring.
Solve the following system of linear equations using elimination. 3r- y=5 x=y=1
1 answer:
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Answer:
So on this case the 97.5% confidence interval would be given by (6.360;9.080)
Step-by-step explanation:
For this case we assume the deviation given as s =2.5 and the mean
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)
s=2.5 represent the sample standard deviation
n=20 represent the sample size
Solution to the problem
The confidence interval for the mean is given by the following formula:
(1)
In order to calculate the critical value we need to find first the degrees of freedom, given by:
Since the Confidence is 0.975 or 97.5%, the value of and
, and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.0125,19)".And we see that
Now we have everything in order to replace into formula (1):
So on this case the 97.5% confidence interval would be given by (6.360;9.080)