Mary Jo takes her son to get a haircut at the barbershop. The total cost of the haircut is $12.60, including a 20% tip. How much
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Answer:
A sample size of 392 is required.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of
, we have the following confidence interval of proportions.
In which
z is the zscore that has a pvalue of .
The margin of error is:
18% of students struggle in their classes because they don't spend more than 8 hours studying independently outside of a 4-unit class.
This means that
99% confidence level
So , z is the value of Z that has a pvalue of
, so
.
You would like to be 99% confident that your estimate is within 5% of the true population proportion. How large of a sample size is required?
A sample size of n is required.
n is found when M = 0.05. So
Rounding up:
A sample size of 392 is required.