The Total solution for NCERT class 6-12
Let E1 bethe event of choosing the bag I, E2 be the event of choosingthe bag say bag II and A be the event of drawing a red ball.
Then P (E1)= P (E2) = 1/2
Also P (A|E1)= P (drawing a red ball from bag I) = 4/8 = ½
And P (A|E2)= P (drawing a red ball from bag II) = 2/8 = ¼
Now the probability ofdrawing a ball from bag I, being given that it is red, is P (E1|A).
By using Bayes’theorem, we have: