# binomial distribution question

hello everyone!
please could someone help me with this question?

In a particular area 30% of men and 20% of women are overweight and there are four men and three women working in an office there. Find the probabillity that there are 2 overweight people in the office.

if someone could just tell me how to go about it, i dont think i actually need to see the working, i just dont know what to do. i've already worked out the probability of 0, 1 or 2 overweight men and 0, 1 or 2 overweight women.

Thanks, rep available obviously
P(2 fat people) = P(exactly 2 fat men and no fat women) + P(exactly 2 fat women and no fat men) + P(exactly 1 fat man and 1 fat woman)
aha! thats what i thought! but how do i work out the prob of 1 fat man and 1 fat woman? do i multiply them or add them or what?
thank you james xxxxx
Jonquil
aha! thats what i thought! but how do i work out the prob of 1 fat man and 1 fat woman? do i multiply them or add them or what?
thank you james xxxxx

Multiply them. They're independent events.
ohhhhhh! i get it. i wasnt including P(X=0) each time i did the prob of 2 fat people of the same sex. i get it now thanks guys
I like the way we went from "overweight" to "fat"!
James Gurung
I like the way we went from "overweight" to "fat"!

I won't inform the H&R crew if you won't.
was just thinking that actually apologies! xxx
Original post by Jonquil
hello everyone!
please could someone help me with this question?

In a particular area 30% of men and 20% of women are overweight and there are four men and three women working in an office there. Find the probabillity that there are 2 overweight people in the office.

if someone could just tell me how to go about it, i dont think i actually need to see the working, i just dont know what to do. i've already worked out the probability of 0, 1 or 2 overweight men and 0, 1 or 2 overweight women.

Thanks, rep available obviously

I'm struggling with finding the probability that there are 0 overweight men. I can't get the right fraction to use but I'm pretty sure its 7C0 (something)^0 (something)^7??
Original post by ndelfava
I'm struggling with finding the probability that there are 0 overweight men. I can't get the right fraction to use but I'm pretty sure its 7C0 (something)^0 (something)^7??

Don't know if the relevant information has been posted, but going on the original post and yours:

It is given that there are 4 men (of the seven), so for there to be 0 overweight men, you're interest in 4C0 (P man overweight)^0(P man not overweight)^4, or putting it more simply P(man not overweight)^4.
Original post by ndelfava
I'm struggling with finding the probability that there are 0 overweight men. I can't get the right fraction to use but I'm pretty sure its 7C0 (something)^0 (something)^7??

Where did you see this question from out of interest? It doesn’t feel like a question you’d see in a modern textbook
Original post by Notnek
Where did you see this question from out of interest? It doesn’t feel like a question you’d see in a modern textbook

AQA A Level Mathematics Year 1 (AS) (Aqa a Level As)
by Sophie Goldie, Susan Whitehouse , et al.

ISBN 9781510455580

(edited 4 years ago)
Original post by ghostwalker
AQA A Level Mathematics Year 1 (AS) (Aqa a Level As)
by Sophie Goldie, Susan Whitehouse , et al.

ISBN 9781510455580

Thanks. That’s a new textbook although the question is slightly different. I wonder if “overweight” was replaced with “underweight”
Original post by Notnek
Thanks. That’s a new textbook although the question is slightly different. I wonder if “overweight” was replaced with “underweight”

My bad - didn't check the detail. Suspect you're correct; further digging produces a couple of volumes from around 2011 that use "overweight".