We should find the number of possible ways the student can arrange 10 participants from total 40 volunteers. We should find the number of combinations.
Combination is a way of selecting r items (participants) from a set (collection) of n items (volunteers). The order of selection of the items does not matter in this situation.
In our case: r=10 , n=40
The formula is: C=n!/(n-r)!*r!=40!/(30!*10!)=40*39*...*30!/30!*10*9*8*7**...*2=
40*39*...*31/10*9*8*7**...*2=4*39*...*31/9*8*7**...*2=847660528
