Thread: PROB/STAT help

1.There are 12 apples in a bag. Four of them have worms in them. Two apples are pulled from the bag at random, find the probability that neither has a worm in it.

2.A company car pool consists of 40% fords, 20% chryslers and 40% Hondas. While each honda has a passenger side airbag, only 50% of the fords and 60% of the chryslers do. A car is selected at random from the car pool. Determine the probability that it has a passenger side airbag.

i know these are easy but, this class is hard any help will help

How many ways can one pick two ‘good’ apples?
How many ways can one pick two any apples?
Now divide.

let A = good apple. 8/12= P(A)
b = bad apple.4/12 =P(A^c)
p(B|A)= probability second apple is bad one given that the first apple is good =4/12

p(B|A^c)=8/11 eleven it is not but back at the bag

p(B^c|A)= 7/11 eleven it is not but back at the bag
p(B^c|A^c) =3/11 eleven it is not but back at the bag

p(B) =P(B|A)P(A)+p(B^c|A)P(A^c)
= 4/12.8/12+7/11.4/12=