Kelly went to a store to purchase a coffee pot. She will use a coupon for 20% off. She can calculate the cost before sales tax u
1 answer:
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Answer:
(b)
Rounded up would be n =296
Step-by-step explanation:
Assuming this previous info: She randomly interested in the p selects 100 engineering majors, and 26 of them said they earned an A in Calc 1.
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".
Solution to the problem
The population proportion have the following distribution
The margin of error for the proportion interval is given by this formula:
(a)
If solve n from equation (a) we got:
(b)
In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 95% of confidence, our significance level would be given by and
. And the critical value would be given by:
Thes estimated proportion is
And replacing we got:
(b)
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