June 2003 S1

[gnevillesucks]

House No1: 4C 1P 2G
House No2: 2C 2P 3G
House No3: 1C, 1G

Q6(iii)
Given that the person chosen by the method in part (ii) is a grandparent, calculate the probability that there is also a parent living in the house.

How do we do this question?
PS: The answer to part (ii) is 17/42

 

[weesha]

p(P and G) that is sum up the probablility of Grand parents of those houses where parents are present ( house no 1 and 2)
divide by p(G) in part (ii)