# statistics project help (z-value)?

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Anonymous
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okay so i have a project im working on for extra credit for my stat class. i got halfway through the project and i am stuck. we are supposed to generate or find a problem and solve it. i found one from a book and worked everything out but i have a problem getting the z-value. to make things clear i will just post the questions so i can get some help. my problem is with question 6 and 7. someone help

Before writing the project, find or generate a set of quantitive data that should be normally distributed, i.e. measurements from nature. The data should:
a) either come from a survey you conducted, or from an existing set not in your statistics text book. Almanacs from the library and the internet are a good source of data sets.
b) have at least 30 data points.
1.Write an introductory paragraph explaining your project.
2.List your data set.
3.Calculate the:( You may use Excel or your calculator.)
a)mean, identify it as either or .
b)standard deviation, identify it as either  or s.
4.Make a frequency distribution. Include columns for frequency, relative frequency, and cumulative frequency. If your data has 10 or more different values, you may want to group the data into classes. Use at least 7 classes.
5.Draw a histogram using Excel.
6.Using the z-score table find the value of z that should have 75% of the data less than it.
7.Translate the z from step #6 to an x using the mean and standard deviation from step#3