Question

A bag contains 3 white 2 red balls .A ball is drawn and another ball is drawn without replacing frist ball.Then the probability of second ball to be red is

Answer 1

Probability that this draw of red ball is due to the drawing of red ball from the first bag

Case 1: Black ball was picked from Bag 1 and then a Red is picked from Bag 2

P(R) = 25∗410=85025∗410=850

Case 2: Red ball was picked from Bag 1 and then a Red is picked from Bag 2

P(R) =35∗510=155035∗510=1550

We need the probability of occurrence off Case 2:

Hence P(Case 2) =1550/(850+1550)=1523