The Student Room Group
Uni students - Complete our survey >>
Uni students - Complete our survey >>
Uni students - Complete our survey >>

This discussion is now closed.

Check out other Related discussions

Simple Stats Question

Hello can somebody please help me understand the answer to this question.

Now it involves a Venn Diagram. Out of the sample of 50 people 2 people are picked at random. I have to find the probability that exactly 1 of them would recycle kitchen waste. The total number of people recycling kitchen waste is 18 out of the 50 people. That means if the first person picked is a kitchen waste recycler there will be 32 people left of the 49 people who do not recycle kitchen waste.

So I calculate the answer by doing (18/50)*(32/49) however from the mark scheme the correct answer is 2*(18/50)*(32/49) so the answer is double my answer of 0.235. I don't see why you have to multiple by 2. Can someone please explain the reason to me please?
Reply 1
Avatar for Unknown?
Unknown?
OP
12
Please any help?
Reply 2
Avatar for ztibor
ztibor
10
Unknown?
Hello can somebody please help me understand the answer to this question.

Now it involves a Venn Diagram. Out of the sample of 50 people 2 people are picked at random. I have to find the probability that exactly 1 of them would recycle kitchen waste. The total number of people recycling kitchen waste is 18 out of the 50 people. That means if the first person picked is a kitchen waste recycler there will be 32 people left of the 49 people who do not recycle kitchen waste.

So I calculate the answer by doing (18/50)*(32/49) however from the mark scheme the correct answer is 2*(18/50)*(32/49) so the answer is double my answer of 0.235. I don't see why you have to multiple by 2. Can someone please explain the reason to me please?


Your logic is correct but you have 2 people for that, 1 of them recycle kitchen waste. So your answer is the possibilty only of that, one of them will recycle, but same the possibility of that, the second people will do.
Unknown?
Please any help?


it happens like this
(incase of picking randomly..there is no fixed order?)
answer.
=(recycle x not recycle) + (not recycle x recycle)

(numerically)

=(18/50 x 32/49) + (32/50 x 18/49)
=0.470

(instead of adding you can multiply by 2..but for your understanding i did it)

Related discussions

Latest

Trending

Trending

Articles for you