Question

There are 20 students on the school's student council. A special homecoming dance committee is to be formed by randomly selecting 7 students from student council. How many possible committees can be formed? 5,040 77,520 390,700,800

Answer 1

Answer: 77520

i got it right in my exam

Answer 2

You can choose from 20 students for the first student, 19 for the second, 18 for the third, ..., 14 for the seventh student.

That gives you 20 * 19 * 18 * 17 * 16 * 15 * 14.

That number would allow you to write the students in different order. Since order here does not matter, any group with the same students in any order is the same group, you need to divide by the number of way you can order 7 items. Divide by 7 * 6 * 5 * 4 * 3 * 2 * 1

(20 * 19 * 18 * 17 * 16 * 15 * 14)/(7 * 6 * 5 * 4 * 3 * 2 * 1) = 77,520

Answer: 77,520