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Mean and standard deviation of a binomial random variable

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Problem

Ms. Davis is doing an activity with her statistics students where she gives them a 20-question multiple choice test, and they know none of the answers. Students need to guess on every question, and each question has 5 possible choices, 1 of which is correct.
What are the mean and standard deviation of the number of questions that each student gets correct?
You may round your answers to the nearest tenth.
mean:
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4
  • an exact decimal, like 0.75
  • a multiple of pi, like 12 pi or 2/3 pi
correct
standard deviation:
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4
  • an exact decimal, like 0.75
  • a multiple of pi, like 12 pi or 2/3 pi
correct
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