Probabilities & z scores

[jefgif]

Suppose you have a standardized test that is normally distributed with a mean of 47 and a standard deviation of 9. What is the probability that your actual score will be between 40 and 50 inclusive ??
How do Z scores figure into the equation ????

 

[wjm11]

Suppose you have a standardized test that is normally distributed with a mean of 47 and a standard deviation of 9. What is the probability that your actual score will be between 40 and 50 inclusive ??
How do Z scores figure into the equation ????

The z score tells you how many standard deviations a given score is from the mean score. You can then look up the z score in a table that will tell you what percentage of the total population that z score represents. If you do this with two different scores, you can subtract one percentage from the other to find the percentage of population between the two scores. That answer will be your probability.

 

[jefgif]

Thank you. I knew what z scores represented but was not sure what to do with the two z scores to get the answer.