How many ways can 30 students be arranged in a 4- student line?

1 Answer
Apr 20, 2016

Answer:

#657,720# ways

Explanation:

I have assumed that what is meant is:
"How may ways can a group of 4 students be extracted from a group of 30 students, when the order of extraction is significant?"

In this case:
#color(white)("XXX")#There are #30# candidates for the first selection
#color(white)("XXX")#For each of the first selections there are #29# candidates for the second selection
#color(white)("XXX")#For each of these first and second selections there are #28# candidates for the third selection.
#color(white)("XXX")#For each of these first, second, and third selections there are #27# candidates for the fourth selection.

Therefore there are
#color(white)("XXX")30xx29xx28xx27=657,720# possible selections.