What is a Normal distribution?
Normal distribution probability refers to a distribution shaped like a bell curve. When you tackle normal distribution in a statistics class, you’re trying to find the area under the curve. The total area is 100% (as a decimal, that’s 1). For more on exactly what a bell curve is all about, see What is a Normal Distribution?
Types of Normal distribution Problems
Normal distribution problems come in six basic types. How do you know that a word problem involves normal distribution? Look for the key phrase “assume the variable is normally distributed” or ”assume the variable is approximately normal.”
How to Solve Normal Distribution Problems
Step 1: Read the problem and identify the pieces of information you are given: for example, you might be given the mean, the standard deviation and the number of randomly selected items.
Step 2: Find the items you identified in step 1 in the second column in the table (GIVEN).
Step 3: Check the third column for what the problem is asking you to do. Then follow the link in the first column for a step-by-step article.
|Post||Given||Asked to find…|
|Normal Distribution word problems less than (click here).||
||The size or probability of “less than” or “fewer than” or “under” a certain amount (i.e. “under $5,000″)|
|Statistics Normal distribution word problems Above (click here).||
||The size or probability of “more than” or “greater than” or “over” a certain amount (i.e. “under $5,000″)|
|Word problems with normal distribution: Between (click here).||
||The size or probability of “in between” (i.e. “in between $5,000 and $10,000″)|
|Normal distribution word problems with solutions: finding Middle percentage (click here).||
||Find the upper and lower limits for a certain given middle percentage|
|“Normal distribution word problems and answers: lower cut off (click here).||
||find the lower cut off point, given an upper percentage|
|Normal distribution word problems finding an upper cut off point (click here).||
||find the upper cut off point, given a lower percentage|