9.58 - 2.2 × 3.5 + 0.32
2 answers:
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Answer:
A sample of 997 is needed.
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 z-score that has a p-value of .
The margin of error is of:
A previous study indicates that the proportion of left-handed golfers is 8%.
This means that
98% confidence level
So , z is the value of Z that has a p-value of
, so
.
How large a sample is needed in order to be 98% confident that the sample proportion will not differ from the true proportion by more than 2%?
This is n for which M = 0.02. So
Rounding up:
A sample of 997 is needed.