## sha0403 2 years ago event A and B in a sample space S have the following probabilities. P(A)=0.4,P(B')=0.3 and P(A intersect B)=0.2... Help me to find number of sample space?

1. srossd

What do you mean by "number of sample space"?

2. sha0403

did u know abt it n(s) in probabilitty? that include all the value of data..

3. srossd

Oh, cardinal number. Generally, you would need more info than that to figure out the cardinal number exactly, but the minimum possible would be 10, I think.

4. srossd

Oh oh ohhhh nevermind. Disregard everything I"ve said so far, I get it now.

5. srossd

So P(B) is 0.3, P(A) = 0.4...wait a minute, those can't be the only events, right?

6. srossd

And just noticed it was P(B'), so P(B) is 0.7, which is even worse :/.

7. sha0403

so,how we identified the n(s)?

8. srossd

Ok, actually, lets say they're not mutually exclusive events (normally that would be explicit, but oh well). So say A contains 4 events, and B contains 7. Their intersection contains 2. So there are 9 events: 4+7-2. Of course, it could be any multiple of 9 too.

9. sha0403

you mean n(s) is 9?

10. srossd

Yeah, n(S)=9, I think that's what they're going for. Sorry I'm not exactly an expert here, but no one else is backing me up, so that's my best guess.

11. sha0403

oh i think that 9 at first but i'm not confident..but after u say that,, i confident now..thank u very much k.. =)