A 95% confidence interval for a population mean was reported to be 152 to 160. The margin of error is:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 4
A confidence interval is (estimate − E, estimate + E), so its length is 2E, where E is the margin of error.
\( \displaystyle E=\frac{160-152}{2} \)
\( =4 \)
Why the other options are incorrect
Option (1) 8 — Incorrect. 8 is the full width of the interval, which is twice the margin of error.
Option (3) 6 — Incorrect. The margin of error is half of 8, which is 4, not 6.
Option (4) 5 — Incorrect. The margin of error is half of 8, which is 4, not 5.