Normal Distribution Problems- Two Common Mistakes

I see many students in my intro statistics courses missing problems related to the normal distribution. Common Mistake #1: One especially common mistake is not using the correct “standard deviation” to find probabilities and percentiles. Consider the following problem...

When do I substract from 1?

Always sketch the normal curve situation first. Remember the Standard Normal Distribution tables almost always give the area/probability from left infinity to the z-value in question; check for sketches on the tables you use to confirm. The Excel Norm.xxx functions...