2 more

[kittysnyde]

Again would appreciate any help!

1. The events A and B are mutually exclusive. If P(A)= .3 and P(B)=.4 what is P(A and B)?

I feel like this might be a trick question? I thought mutually exclusive refered to P(A or B).
Should I assume he meant independent? in which case:

P(A and B)=P(A)*P(B)

=.3 * .4 = .12



2. Given P(A or B)= .25, P(A)= .20 and P(A and B)= .11 find P(B)

I got:
P(A or B)= P(A) + P(B) - P(A and B)

P(B) = P(A or B) - P(A) + P(A and B)

P(B)= .25 - .20 + .11

= .16

 

[pka]

Again would appreciate any help!

1. The events A and B are mutually exclusive. If P(A)= .3 and P(B)=.4 what is P(A and B)?

mutually exclusive means that the events have nothing in common.
Thus \(\displaystyle P(A\cap B)=0~\&~P(A\cup B)=P(A)+P(B).\)