Question

Suppose A and B are dependent events. If P(A|B)=0.25 and P(B)=0.8 , what is P(AuB) ?

Answer 1

Hi Panda,
do you know the formula for
P(A|B) ?

Answer 2

P(AuB)/P(B) ?

Answer 3

close,
its actually
\(P (A|B) = \dfrac{P(A \cap B)}{P(B)}\)

Answer 4

if i did it right wouldn't it be 0.25, and yeah i know i just didn't know how to set it up on the computer

Answer 5

from that
\(P (A \cap B) = 0.25 \times 0.8 =..\)
isn't it ?

Answer 6

also, any other information given ??
like P(A)
?

Answer 7

well the answers are 0.25, 0.85, 0.8, and 0.2 I'm not quite sure ow to get the right answer :/

Answer 8

and no theres not thats it

Answer 9

we now have \(P(A\cap B)\)

using the formula
\(\Large P (A\cup B) = P(A)+P(B)-P(A\cap B)\)

we still need P(A)

Answer 10

I'm trying to figure it out and i don't understand that's all the info i have isn't P(A)=0.25

Answer 11

if A,B are *independent*, then we can solve it...

Answer 12

how is P(A) =0.25 ?

Answer 13

i don't knowI'm just trying to figure things out and the answer was 0.2

Answer 14

maybe the question asked is
\(P(A \cap B)\)

which we already got as
\(P (A \cap B) = 0.25 \times 0.8 =0.2\)

Answer 15

wow.. see i got that but i scewed up by doing more than i needed to :/ thanks for the help tho.

Answer 16

welcome ^_^