Question

A box got 5 black ball and 4 white ball. If keep continuously take 4 balls out, the probability to get black ball is

Answer 1

Answer:

Step-by-step explanation:

7/11

5/11

53/99

48/99

Answer :

C

Solution :

Consider the following events :

E1=Ball drawn from the box is white

E2=Ball drawn from the box is black

A= Getting a black ball from the box after replacing the drawn ball with two balls of opposite colour

P(E1)=49,P(E2)=59,P(A/E1)=711,P(A/E2)=511

∴P(A)=P(E1)P(A/E1)+P(E2)P(A/E2)

=4/9×7/11+5/9×5/11=53/99