Answer :
Therefore , the solution to this problem is confidence interval 95% is given by Z =1.96.
Confidence Interval: What is it?
In frequentist statistics, a confidence interval is the range of estimates for an unknown quantity. 95% is the most frequent confidence level used when calculating confidence intervals, however 90% and 99% are also occasionally used.
a)85 out of 100 paid at the pump using credit card
Thus,
p = proportion of customers who paid at the pump using credit card
= 85/100
= 0.850
Estimated Value of the population proportion = 0.850
b)
Given:
p' = 0.85 ....... Sample Proportion
n = 100 ....... Sample Size
For 95% Confidence interval
α = 0.05, α/2 = 0.025
From z tables of Excel function
Z = [tex]\frac{p'-p}{\sqrt{p(1-p)/n} }[/tex]
we find the z value
z = (0.025) = 1.96
We take the positive value of z
Therefore , the solution to this problem is confidence interval 95% is given by Z =1.96.
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