Thread: Basic Question

Two rooms were stored with tyres. One room was stored with 3 good tyres and 5 spoilt tyres. The other room was stored with 2 good tyres and 5 spoilt tyres.
A mechanic choses one of the room at random and takes out a tyre. Find the probability that the tyre chosen is good.

Since you have been asked to find the probability of only the good tyres,

the probability of him choosing a good tyre from the first room (3/8) and from one of the two rooms (1/2) OR'ed with the probability of him choosing a good tyre from the second room (2/7) and from one of the two rooms (1/2):

( ) + ( )