Suppose you plan to build a 98% confidence interval estimate of a population mean, using a sample of size 121.You will be estimating the population standard deviation with the sample standard deviation.The appropriate t-value for your interval would be ____ which you could approximate with a z score of _______ from the normal table.
A)2.358, 2.33
B)1.289, 2.33
C)1.658, 1.96
D)1.980, 1.96
E)2.617, 2.33

Question

Quizplus · Accepted Answer

For a 98% confidence interval with a sample size of 121 and estimating the population standard deviation with the sample standard deviation, the appropriate t-value should be looked up in the t-distribution table for 120 degrees of freedom (n-1) at the 98% confidence level. However, with large sample sizes (such as 121), the t-distribution approximates the normal distribution, and the z-score for a 98% confidence interval from the normal distribution is approximately 2.33. Therefore, the closest match and appropriate approximation is 2.358 for the t-value, which can be approximated with a z-score of 2.33 for practical purposes.

Suppose You Plan to Build a 98% Confidence Interval Estimate