The z value for a 97.8% confidence interval estimation is
A) 2.02.
B) 1.96.
C) 2.00.
D) 2.29.

Question

Quizplus · Accepted Answer

To find the z value for a 97.8% confidence interval estimation, we need to find the z value that has an area of 0.989 on the right tail of the standard normal distribution. Using a standard normal distribution table, we can see that the closest z value is 2.33, which corresponds to an area of 0.9901. However, since we are looking for a two-tailed interval, we need to divide the significance level (1 - confidence level) by 2, which gives us 0.011. We then need to find the z value that corresponds to an area of 0.0055 on each tail. The closest z value is 2.54, but since it is not one of the available answer choices, the most appropriate option is D, 2.29, which corresponds to an area of 0.0114 on each tail.

The Z Value for a 97