CBSE Class 12-science Answered

Bag-1  B₁ contains 8 red balls and 2 black balls .

Bag-2  B₂ contains 7 red balls and 5 black balls .

Let P(B₁) and P(B₂) be the probability of selecting the bag-1 and bag-2 respectively to pick a ball.

P(B₁) = P(B₂) = 1/2

Let P( R | B₁ ) be the probability of selectring red ball from bag-1.

Let P( R | B₂ ) be the probability of selectring red ball from bag-2.

We get the above coditional probabilites as

P( R | B₁ ) = 8/10   

P( R | B₂ ) = 7/12

Probabity of  randomly picked ball is red and is picked from bag-1 is P(B₁ | R ) is