Keith S. answered • 08/20/20
Ph.D Student & Tutor Specializing in Mathematics
I was extremely distracted during answer 3, so please note that the final answer to part b is 1/4! Even though I may have said 1/6 and written 1/16. Sorry about that!!!
Keith S.
Oh wow that did not format well. Let me know if any of that needs reclarification08/20/20
Aisha H.
is it possible to format it better08/20/20
Keith S.
I can't really know how the formatting will end up from my end. Just look for the "a)', "b)", and "c)" sections, and write those sections down in a less chaotic way, then see if that helps to make sense of them08/20/20
Elaine C.
I got around 1.25 for b) is there any way to explain it?08/20/20
Keith S.
Right. So first off, your answer will have to be between 0 and 1. Now, for part B, you need to know the probability of at least 2 Linguits, but that's just the opposite of at most 1 linguist (which makes the answer just 1 minus the probability of at most 1 linguist). That is 2 cases: 0 or 1 linguists. If there are 0 linguists, then the 8 spots can be filled by any of the 20 remaining people. That's 20C8. For the 1 case, there are 4C1 ways to choose 1 linguist, times 20C7 for the 7 remaining spots out of 20 people. Thats 20C8 + 4*20C7. Now divide that sum by 24C8, since that's how many total ways to make this 8-person group out of all of the 24 people. Thus, the full answer is 1- (20C8 +4*20C7)/(24C8) which is .4071.08/20/20
Elaine C.
Thank you for the explanation, I caught the mistake I made and got the final answer .407108/20/20
Vinu P.
thank you for your help, i understand it much better now!08/20/20
Vinu P.
for the first question can it be arranged in 6 ways cause you can do N,BRO,W or BRO,N,W or N,W,BRO so instead the probability would be 3!/5!?08/20/20
Sehun O.
yea @ vinu you are correct. Idk what keith is on but he is def wrong about question 1 being 1/40. the answer is 1/20, or 5%.08/20/20
Vinu P.
ok tyy i was honestly thinking that i was wrong lol08/20/20
Keith S.
I don't think it will let me post a second video. In that case, Probability=#EventYou'reAskedAbout/#TotalWays a) 7C7*(24-7)C1 = 7*17, all divided by 24C8 =====.0001618 b) P(>2 Linguists) = 1 - P(0 Linguists) - P(1 Linguist) = = 1 - (20C8 - 4C1*20C7)/24C8 ====== .4071 c) There are two options in this scenario: P(3 Chems, 1 Bio, 4 Else) = (10C3*7C1*7C4) / 24C8 + P(6 Chems, 2 Bio, 0 Else) = (10C6*7C2*7C0) / 24C8 = 33810 / 735471 == .0459708/20/20