Dinner costs $42. With 18% gratuity, how much will you pay in total?
2 answers:
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Answer:
a) n = 1037.
b) n = 1026.
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:
99% confidence level
So , z is the value of Z that has a pvalue of
, so
.
(a) Assume that nothing is known about the percentage to be estimated.
We need to find n when M = 0.04.
We dont know the percentage to be estimated, so we use , which is when we are going to need the largest sample size.
Rounding up
n = 1037.
(b) Assume prior studies have shown that about 55% of full-time students earn bachelor's degrees in four years or less.
So
Rounding up
n = 1026.