A professor must randomly select 4 students to participate in a mock debate. There are 20 students in his class. In how many different ways can these
students be selected, if the order of selection does not matter?

Step-by-step explanation:

We can use combinations

20 choose 4:

20!/(16!*4!)

= (20*19*18*17)/4!

= 4845

3/4 ÷ 3/4

step-by-step explanation:

basically divide any proper fraction with itself to fit the criteria.

so if we are using 3/4, then:

3/4 ÷ 3/4 = 1

so 1 is the quotient.

and the numerators for both these fractions is 3.   and if we divide the numerators:

3 ÷ 3 = 1

we see that quotient is equal to our original quotient as well.

45

step-by-step explanation: