Question

A 90% confidence interval is found to be (120, 140). What is the margin oferror?

Answer 1

Given:

`C.I=(120,140)`

The margin of error is equal to half the width of the entire confidence interval.

Hence, the width of the confidence interval is;

`140-120=20`

Hence, the margin of error is half the width of the confidence interval.

`\begin{gathered} margin\text{ of error}=(20)/(2) \\ margin\text{ of error}=10 \end{gathered}`

Therefore, OPTION B is the correct answer.