Thread: Confidence Interval

Hello Everyone,

This is my first time posting. I'm working on a statistics problem that I'm having difficulty understanding. Here is the problem:

The Praxis II test was given to a sample of 1573 prospective teachers. The mean of these scores was 1053 and the standard deviation was 92.
a.) Give a 95% confidence interval (μ ± 2ơ) for the mean (average) score in the population of all young women.
b.) Suppose that a sample of 300 prospective teachers had produced the same mean and standard deviation. Again, give the 95% confidence interval (μ ± 2ơ) for the mean (average) score in this case.

I have gone over and over but I'm not understanding something because it feels like information is missing based on what I have been doing. I appreciate any help with understanding the problem.

Originally Posted by pbball

Hello Everyone,

This is my first time posting. I'm working on a statistics problem that I'm having difficulty understanding. Here is the problem:

The Praxis II test was given to a sample of 1573 prospective teachers. The mean of these scores was 1053 and the standard deviation was 92.
a.) Give a 95% confidence interval (μ ± 2ơ) for the mean (average) score in the population of all young women.
b.) Suppose that a sample of 300 prospective teachers had produced the same mean and standard deviation. Again, give the 95% confidence interval (μ ± 2ơ) for the mean (average) score in this case.

I have gone over and over but I'm not understanding something because it feels like information is missing based on what I have been doing. I appreciate any help with understanding the problem.

You will find several worked examples of this type of question on these boards.

In both cases you have the values of n, and . You only have to decide whether to use the t- or z-statistic.

Why do you think there is missing information? Where exactly are you stuck?