Biology Probability help
Warning: If you do not know what the phrase nCr means, please do not respond with an "I think it's this, but can't prove it," Thank you, Feel free to bumb the thread if you can't answer
I was assigned this biology problem with "Swapping body fluids." There is initially, 1 person "infected" with a disease, (put base in cup that when reacts with other liquid turns purple, swapping body fluids is combining cups and both people get half the cup).
There are 25 people in the class and there are 3 swaps per person, with one additional swap at the end that is not made, but feel free to do this with a number divisible by 3.
I know that I should do ways to get infected over total ways to swap
This would indicate 25c2 ways to swap initially. Then the second one would be 24c2, and then 23c2. Multiplying these together yields 20,948,400, but calculatin 300c3 yield 4455100. Which of these would I do to find the total combinations of ways to swap.
Next part is the ways to get infected. I know that the lower limit for chance to be infected is 8/25, because exactly 8 of the 25 people will be infected, except in the case that the last person who only makes 2 swaps is infected.
Help?
Thanks in advance.
3 Comments • Newest first
[quote=liquidman2]i don't know if you're trolling or just incredibly stupid.
how far off you are is not even funny.[/quote]
Sorry meant to be reciprocal, 1/(25c3). 1 in 2300
Stop stealing thread pl0x?
Edit- its nPr fo sho, or 25P3 or 13800. 1 in 13800. NVM
Think i got it, 25 (number of people initialy infected ways to do ) *24*2*23*3*22*1/((25c2)c3)
And yes I know the answer to my problem is 8/25, but I want a different number using ways to be infected
Thanks, now I realize it's 25*24*23*22*2*3*4/((25C2)P3)
[quote=liquidman2]I dont know but isn't that math probability?
Example. There are 25 students, a teacher wants to guess which 3 will come to class first, in specific order.
What is the probability she will get it right? (Lol, noone will get this correct)[/quote]
amount of specific orders she picks*(25c3) O_O.
And math probability help (I don't know any other kind), with a weird biology twist on it.
Well then... Have my bumb.