The probability of the first item being good is 11/15.
Since we have taken 1 item out the remaining total is now 14, so the probability of getting a defective item is now 4/14.
Now you multiply the probabilities together to get (11/15)(2/7)=22/105
I'm not sure does anyone else know the answer?
4:1 means for every four soccer player there is 1 volleyball player
that means there are four times the number of soccer players than volleyball players
Use the identity P(A ∪ B) = P(A)+P(B)-P(A ∩ B)
P(A)=0.50
P(B)=0.60
P(A ∪ B) = 0.30
=>
P(A ∪ B) = P(A)+P(B)-P(A ∩ B)
=(0.50+0.60)-0.30
=0.80
