A 90% confidence interval for a proportion is found to be (0.60, 0.68). What is the margin of error?
A. 0.03
B. 0.06
C. 0.02
D. 0.04
The margin of error is the half-width of the confidence interval.
To find the margin of error, we need to find the distance between the point estimate (proportion) and the bound of the confidence interval in either direction.
The point estimate is the midpoint of the confidence interval:
Point estimate = (0.60 + 0.68) / 2 = 0.64
Therefore, the margin of error is the distance from the point estimate (0.64) to either bound of the interval:
0.64 - 0.60 = 0.04
So, the margin of error is 0.04.
Therefore, the correct answer is:
D. 0.04