SOLUTION: In a class there are 45 ways to make pairs of students. How many students are there in the class?

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Question 1116438: In a class there are 45 ways to make pairs of
students. How many students are there in the class?
Answer by ikleyn(52772) About Me  (Show Source):
You can put this solution on YOUR website!
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If "n" is the number of students in the class, then the number of possible pairs is %28n%2A%28n-1%29%29%2F2.


Your equation is


%28n%2A%28n-1%29%29%2F2 = 45,   or   n*(n-1) = 90,  which implies  n = 10.


Answer.  There are 10 students in the class.