Rachel has 8/12 of a fun of frosting. If she used 1/4 of it, how much was left?
2 answers:
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Answer:
n=126
Step-by-step explanation:
Data given and previous concepts
represent the sample mean
represent the sample deviation
n=32 represent the sample size
Confidence =0.95 or 95%
represent the significance level
ME= 2 represent the margin of error required
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".
Assuming the X follows a normal distribution
Solution to the problem
Since we don't have the population deviation. We know that the margin of error for a confidence interval is given by:
(1)
The next step would be find the value of ,
and
. The degrees of freedom are given by:
Using the normal standard table, excel or a calculator we see that:
And the code in excel is this one: "=T.INV(1-0.025,31)"
If we solve for n from formula (1) we got:
And we have everything to replace into the formula:
And if we round up the answer we see that the value of n to ensure the margin of error required is n=126.