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 statement: A bank auditor claims that credit card balances are normally distributed, with a mean of […]

No Standard Deviation? How do I get the standardized test statistic?

I get this question a lot in my BUS 233 Business Statistics course. It comes when students see a problem similar to the following in their homework or on a quiz: In a sample of 1000 home buyers, you find that 457 home buyers found their real estate agent through a friend. At α=0.08, can […]