Walden’s family is shopping for a reclining chair. The chair the family decided on has a retail price of $800 plus 5% sales tax
2 answers:
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Answer:
We need a sample size of least 119
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:
95% confidence level
So , z is the value of Z that has a pvalue of
, so
.
Sample size needed
At least n, in which n is found when
We don't know the proportion, so we use , which is when we would need the largest sample size.
Rounding up
We need a sample size of least 119