Question

question 5 of 25
an 80% confidence interval is found to be (200, 240). what is the margin of error?
a. 40
b. 16
c. 20
d. 32

Explanation:

Step1: Find the center of the interval

The center of the interval \((a,b)\) is \(\frac{a + b}{2}\). Here \(a = 200\) and \(b=240\), so the center \(c=\frac{200 + 240}{2}=\frac{440}{2}=220\).

Step2: Calculate the margin of error

The margin of error \(E\) is given by \(E=b - c\) (or \(E=c - a\)). Using \(b = 240\) and \(c = 220\), we get \(E=240-220 = 20\).

Answer:

C. 20