SOLUTION: a math teacher is preparing a quiz for all of the students in grade 12. she wants to give each student the same questions,but have each student's questions appear in a different or

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Question 951200: a math teacher is preparing a quiz for all of the students in grade 12. she wants to give each student the same questions,but have each student's questions appear in a different order. if there are 128 students in the grade 12 class, what is the least number of questions the quiz must contain so everyone gets a test with the questions in the different order
Answer by Edwin McCravy(20055) About Me  (Show Source):
You can put this solution on YOUR website!
If the test has n questions, they can be arranged
in n! ways:


If the test has     they can be
  this many         arranged in
  questions,       this many ways
      1              1! = 1
      2              2! = 2
      3              3! = 6
      4              4! = 24
      5              5! = 120   <-- not quite enough 
      6              6! = 720   <-- more than enough

So the test must have 6 questions.

Edwin