Question

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 number of selections does not matter?

Answer 1

If the order doesn't matter the it's

`C(20,4)=(20!)/(4!16!)=(17\cdot18\cdot19\cdot20)/(2\cdot3\cdot4)=4845`

Answer 2

Different ways can these students be selected = 4845

Explanation:

Number of combinations possible from n number of population if r people are selected is
`^nC_r`

Here n = 20 and r = 4

Different ways can these students be selected =
`^(20)C_4`

`^(20)C_4=(20* 19* 18* 17)/(1* 2* 3* 4)=4845`

Different ways can these students be selected = 4845