Question

Mrs. Jones buys two toys for her son. The probability that the first toy is defective is 1/3, and the probability that the second toy is defective given that the first toy is defective is 1/5. What is the probability that both toys are defective?

Answer 1

P( A & B) = P( A) * P ( B |A )

Answer 2

That's the one thing I am not understanding.

Answer 3

I don't understand the product rule functions.

Answer 4

Or at least the placement of the probabilities.

Answer 5

@perl

Answer 6

Let
A = the event that first toy is defective
B = the event that second toy chosen is defective
so we are given
P(A) = 1/3
P(B|A) = 1/5

B|A means "event B given that you know event A has occured"

now we are asked to find
P( A & B )
the rule is
P( A & B ) = P(A) * P(B|A)

so we plug in

P(A& B ) = 1/3 * 1/5