Students struggled with…

  • Deciphering between a problem selecting an individual from a population versus a sample from a population.
  • Checking the appropriate conditions for standard deviation and Normal approximations.


  • Instead of thinking of selecting an individual versus selecting a sample as two different types of questions with two different sets of formulas, think of both problems as if you are being asked about a sample.  When selecting an individual from a population this is a sample of size n = 1.
  • We worked hard to develop students conceptual understanding of why the 10% condition and Central Limit Theorem are needed, but students can still mix up which is needed when calculating standard deviation or for checking Normality. This calls for some good old fashioned studying. We made this Chapter 7 Review Sheet so students can easily organize all the formulas and conditions this chapter.

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