A 3-yard roll of waxed paper costs $9.81. What is the price per foot?
1 answer:
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Answer:
a)
The 95% confidence interval would be given by (0.799;0.847)
b)
And rounded up we have that n=622
c)
And rounded up we have that n=1068
Step-by-step explanation:
Part a
In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 95% of confidence, our significance level would be given by and
. And the critical value would be given by:
The confidence interval for the mean is given by the following formula:
If we replace the values obtained we got:
The 95% confidence interval would be given by (0.799;0.847)
Part b
The margin of error for the proportion interval is given by this formula:
(a)
And on this case we have that and we are interested in order to find the value of n, if we solve n from equation (a) we got:
(b)
And replacing into equation (b) the values from part a we got:
And rounded up we have that n=622
Part c
And rounded up we have that n=1068