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
$C(20,4)=\dfrac{20!}{4!16!}=\dfrac{17\cdot18\cdot19\cdot20}{2\cdot3\cdot4}=4845$

Answer 2

Answer:

Different ways can these students be selected = 4845

Step-by-step 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 = $^{20}C_4$

$^{20}C_4=\frac{20\times 19\times 18\times 17}{1\times 2\times 3\times 4}=4845$

Different ways can these students be selected = 4845