There are 9 students in a class. The teacher chooses 2 students to go to the library. The order in which they are chosen does not matter. How many ways are there to choose the students?A.81B.504C.72D.36
Question
There are 9 students in a class. The teacher chooses 2 students to go to the library. The order in which they are chosen does not matter. How many ways are there to choose the students?A.81B.504C.72D.36
Solution
The problem can be solved using the combination formula which is nCr = n! / r!(n-r)!.
Here, n is the total number of students, which is 9, and r is the number of students to be chosen, which is 2.
So, the number of ways to choose 2 students out of 9 is 9C2 = 9! / 2!(9-2)! = 36.
So, the answer is D.36.
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