<p>did mine a different way… 4 people with 2 spots to go = 2 * 2* 2* 2 = 16. but then we’d have to take out the two scenarios in which there would be 4 people in one vehicle (all bus or all van). where the hell did u guys learn this “4cnr3” stuff, by the way? i took honors precalc in a fairfax county school (the richest county in the nation according to Forbes) and didnt learn this at all. i felt like i had to mention the county just to show i dont go to some low end school either lol.</p>
<p>^I love Fairfax (sort of)! Anyways, I think the way people before have written it has led to some confusion. nCr is the choose function where you have n people and have to choose r from among these, where order does not matter. So, the best way, imo, to write out four choose three would be 4C3 (4 replaces the n and 3 replaces the r). I don’t know if you learned choose and permute functions, but you should know them, especially for these standardized tests.</p>
<p>On another note, I figured out that 16 is 4C3+4C3+4c2+4C4+4C4=4+4+6+1+1. Still don’t know how/if you can do this with permutations, though. Maybe 4*4P3 (which equals 16?).</p>