SOLUTION: An instructor has written 20 problems. Five of these are so important that she
assigns them to every student. In addition, each student is assigned five other
problems. In how
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-> SOLUTION: An instructor has written 20 problems. Five of these are so important that she
assigns them to every student. In addition, each student is assigned five other
problems. In how
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Question 1145544: An instructor has written 20 problems. Five of these are so important that she
assigns them to every student. In addition, each student is assigned five other
problems. In how many ways can she assign problems to a student?
You can put this solution on YOUR website! An instructor has written 20 problems. Five of these are so important that she
assigns them to every student. In addition, each student is assigned five other
problems. In how many ways can she assign problems to a student?
Problem group A: the 5 problems that every student necessarily gets.
Problem group B: the 15 problems that NOT every student necessarily gets, but only
5 of them.
A student gets all five problems from problem group A in 5C5=1 way.
A student gets five problems from problem group B in 15C5=3003 ways.
Answer 1×3003 = 3003 ways.
Edwin
