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Normal Distribution Probability in Excel: All Versions up to 2016

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Microsoft Excel for statistics > Normal Distribution Probability in Excel

Before you begin, you might find it helpful to review what a normal distribution is. See: What is a normal distribution?
You can also review what different types of word problems you’re likely to come across. See:
Normal distributions Word Problems.


Watch the video, or read the steps below. Update 6/4/2016: Although I’m using an older version of Excel in this video, the steps are exactly the same for Excel 2016:

How to Calculate Normal Distribution Probability in Excel

normal distribution probability in Excel
While it’s possible to look up probabilities for a normal distribution using the z-table, it’s actually much easier to calculate probabilities in Excel for a couple of reasons. First, there’s no looking at a table; the NORMDIST function does the hard work for you. Second, Excel does the intermediate calculations for you. Most calculation errors happen in an intermediate step (such as calculating the z-score to look up) rather than the actual z-score itself. Excel can handle three types of probability calculations: more than, less than, and in between. These instructions work for Excel 2007 and Excel 2010.

Sample Question: Suppose that a contaminant in samples from a city’s water supply has a mean of 500 ppm and a standard deviation of 100 ppm. What is the probability that bacteria in a randomly selected water sample will be: 1/ less than 600 ppm 2/More than 600 ppm 3/between 400 and 600 ppm?

Calculate Normal Distribution Probability in Excel: Less than

Step 1: Click an empty cell.

Step 2: Click “Insert Formula”.

Step 3: Type “Normdist” into the search box and then click “Go.”

Step 4: Select “NORMDIST” from the list and then click “OK” to open the Function Arguments window.

Step 5: Enter your data into the box. For this example, type “600” in the X box, “500” in the Mean box, “100” in the Standard Deviation box and “true” in the cumulative box..


Step 6: Click “OK.”. This returns 0.84134474 in the cell you clicked in Step 1, which is the probability of getting under 600 ppm.

Calculate Normal Distribution Probability in Excel: More than

Step 7: Subtract your answer from Step 7 (above) from 1:
1-0.84134474= 0.158653.

Calculate Normal Distribution Probability in Excel: Between

Step 8: Repeat Steps 1 through 8 for the second value, which for this example is 400. The probability is 0.15865526.
Step 9: Subtract the larger probability from the smaller probability. In this example:
0.84134474 – 0.15865526 = 0.68269

That’s it!

References

Agresti A. (1990) Categorical Data Analysis. John Wiley and Sons, New York.
Gonick, L. (1993). The Cartoon Guide to Statistics. HarperPerennial.
Vogt, W.P. (2005). Dictionary of Statistics & Methodology: A Nontechnical Guide for the Social Sciences. SAGE.
Wheelan, C. (2014). Naked Statistics. W. W. Norton & Company

CITE THIS AS:
Stephanie Glen. "Normal Distribution Probability in Excel: All Versions up to 2016" From StatisticsHowTo.com: Elementary Statistics for the rest of us! https://www.statisticshowto.com/how-to-calculate-normal-distribution-probability-in-excel/
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