Of 346 items tested,12 are found to be defective.Construct a 98% confidence interval for the percentage of all such items that are defective.
A)(1.18%,5.76%)
B)(0.93%,6.00%)
C)(3.34%,3.59%)
D)(1.85%,5.09%)
E)(0.13%,6.80%)

Question

Quizplus · Accepted Answer

The confidence interval for a proportion can be calculated using the formula: $$CI = \hat{p} \pm Z \sqrt{\frac{\hat{p}(1-\hat{p})}{n}}$$ where $\hat{p}$ is the sample proportion (12/346), $n$ is the sample size (346), and $Z$ is the Z-score corresponding to the confidence level (for 98%, Z ≈ 2.33). Plugging in the values, we get the confidence interval as approximately (1.18%, 5.76%).

Of 346 Items Tested,12 Are Found to Be Defective