Year 12s: what will be the first way you research your future options? >>

S1 Venn diagram help please!!

Hi,
I've been practicing s1 edexcel past papers to prepare for my exam but i find Venn diagrams really confusing. On one of the papers, i'm stuck on one of the questions and still don't understand it after looking at the mark scheme :confused:

Here's a link to the question paper,

S1 Jan 2006

it's question 6c

Here's a link to the mark scheme if you want to look at that,

Mark scheme

Can someone explain it to me please?

Thank You (^_^)

Reply 1

vc94

Formula for conditional probability is: P(A|B) = P(AnB)/P(B)
So here: P(A|B') = P(AnB')/P(B')

Now P(B') = 0.32+0.35=0.67, the parts outside the circle B since B' means the event "not B".
AnB' is the event "A occurs but B does not", so it's just the left hand side of the venn diagram, 0.32.

So answer is 0.32/0.67 = 0.478