# Math Help - calculating p-value

1. ## calculating p-value

Hi all I have another question again. My book gives an example of how to perform hypothesis testing using the p-value approach. After explaining the research problem it gives a step to calculate the test statistic and comes up with z0=2.24 as the test statistic (the pop. std. dev was known and the sample size was 20). The next step after "calculate test statistic" is "calculate p-value". "Given the test statistic z0=2.24, we want to know what is the probability at which an even falls to the right of z0=2.24. In other words, P(z>2.24). From normal table, we find
P(0<z<2.24)=0.4987." I don't really understand how they got that probability because when I look up 2.24 in my normal table I get 0.4875. 0.4987 looks like it corresponds to a zscore of 3.0 or thereabouts. What am I doing wrong? *sad face* lol

2. Originally Posted by peanutbutter
Hi all I have another question again. My book gives an example of how to perform hypothesis testing using the p-value approach. After explaining the research problem it gives a step to calculate the test statistic and comes up with z0=2.24 as the test statistic (the pop. std. dev was known and the sample size was 20). The next step after "calculate test statistic" is "calculate p-value". "Given the test statistic z0=2.24, we want to know what is the probability at which an even falls to the right of z0=2.24. In other words, P(z>2.24). From normal table, we find
P(0<z<2.24)=0.4987." I don't really understand how they got that probability because when I look up 2.24 in my normal table I get 0.4875. 0.4987 looks like it corresponds to a zscore of 3.0 or thereabouts. What am I doing wrong? *sad face* lol
The value you got is the correct one. Time for the author(s) of the book to get better tables