Question

According to the general equation for conditional probability, if P(AB)= 3/10 and P(B) =2/5, what is ? P(A l B)?

1. 1/2
2. 2/5
3. 1/16
4. 3/4

Answer 1

The formula for conditional probablity states that

`P(A | B) = \cfrac{P(A \cap B)}{P(B)}`

Since we know both numerator and denominator, we only need to plug in the values:

`P(A | B) = \cfrac{P(A \cap B)}{P(B)} = \cfrac{(3)/(10)}{(2)/(5)} = \cfrac{3}{10}\cdot\cfrac{5}{2} = \cfrac{3}{4}`