Question

How many different ways can the front row seats be filled with 20 students if the classroom has 4 rows of seats? 1,860,480 116,280 4,845?

Answer 1

we know that

The formula for combinations is

$C=n!/((n-r)!*r!)$

where

n is the total number of objects you choose from

r is the number that you choose to arrange

in this problem

$n=20\\ r=4$

$C=20!/[(20-4)!*4!]\\ C=20!/[(16)!*4!]\\ C=4,845$

therefore

the answer is

$4,845$

Answer 2

1860480 ways the front row seats can be filled