Question

In how many ways can 3
person study groups be
selected from a class of 25
students?
Note: Cr
n!
r!(n-r)!
n
www
Enter

Answer 1

Answer:  2300

Work Shown:

$_{n} C _{r} = \frac{n!}{r!(n-r)!}\\\\_{25} C _{3} = \frac{25!}{3!*(25-3)!}\\\\_{25} C _{3} = \frac{25!}{3!*22!}\\\\_{25} C _{3} = \frac{25*24*23*22!}{3!*22!}\\\\ _{25} C _{3} = \frac{25*24*23}{3!}\\\\ _{25} C _{3} = \frac{25*24*23}{3*2*1}\\\\ _{25} C _{3} = \frac{13800}{6}\\\\ _{25} C _{3} = 2300$