The appliance store where the Scott family shops offers a 7% discount for paying cash. The Scott
1 answer:
You might be interested in
Answer:
The correct answer is
(0.0128, 0.0532)
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of , and a confidence interval
, we have the following confidence interval of proportions.
In which
Z is the zscore that has a pvalue of
For this problem, we have that:
In a random sample of 300 circuits, 10 are defective. This means that and
Calculate a 95% two-sided confidence interval on the fraction of defective circuits produced by this particular tool.
So = 0.05, z is the value of Z that has a pvalue of
, so
.
The lower limit of this interval is:
The upper limit of this interval is:
The correct answer is
(0.0128, 0.0532)
Answer:
1,496 new car buyers
Step-by-step explanation:
The sample size n in Simple Random Sampling is given by
where
z = 1.645 is the critical value for a 90% confidence level (*)
p= 0.33 is the population proportion.
e = 0.02 is the margin of error
so
<em>(*)</em><em>This is a point z such that the area under the Normal curve N(0,1) inside the interval [-z, z] equals 90% = 0.9</em>
It can be obtained in Excel or OpenOffice Calc with
<em>NORMSINV(0.95)</em>