SOLUTION: In how many ways can a group of 24 students be organized into groups of 2 if student number 3 and student number 22 must always be one of the pairs? How can this situation be expre

Algebra ->  Permutations -> SOLUTION: In how many ways can a group of 24 students be organized into groups of 2 if student number 3 and student number 22 must always be one of the pairs? How can this situation be expre      Log On


   

Question 954612: In how many ways can a group of 24 students be organized into groups of 2 if student number 3 and student number 22 must always be one of the pairs? How can this situation be expressed mathematically?
Answer by stanbon(75887) About Me  (Show Source):
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In how many ways can a group of 24 students be organized into groups of 2 if student number 3 and student number 22 must always be one of the pairs? How can this situation be expressed mathematically?
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Let those 2 form one of the pairs.
# of other pairs = 22C2 = (22*21)/2 = 11*21 = 231 other pairs
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Total number of pairs = 1 + 22C2
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cheers,
Stan H.
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