Most Important Selected Qs for JEE AdvancedMathematicsProbability
From an um containing x white and y - x black balls, n balls have been lost, then probability of drawing a white ball
Options
- Abefore the loss is x y
- Bafter the loss is x y for n=1
- Cafter the loss is x y for n=2
- Dafter the loss is x y for n=3
Correct answer
D. after the loss is x y for n=3
Step-by-step solution
Let w be the event that the ball drawn is white Then P(w)= x y When, ball is lost P(w)= x y x-1 y-1 + y-x y x y-1 = x y When 2 balls is lost P(w)= ^x C₂ ^y C₂ x-2 y-2 + ^x C₁ ^ y-x C₁ ^y C₂ x-1 y-2 + y- ^x C₂ ^y C₂ x y-2 = x y Similarly for n =3, P ( w )= x y