Question

A bag contains 4 white and 2 black balls.
4 balls are successively drawn out
without replacement. What is the
probability that they are alternatively of
different colour?

● 2/15
● 1/5
● 2/9
● 1/6​

Answer 1

Answer:

Step-by-step explanation:

Let A=event that the first ball chosen was black and B=event that the first ball chosen was white .

Now event A takes places in the following manner : first ball black with probability 4/7 , second ball with probability 3/7 , third ball with probability 4/7and fourth ball with probability 3/7.

Hence probability of A coming true P(A)=4/7×3/7×4/7×3/7=324274.

Similarly probability of event B happeningP(B) =3 power 2 into 4 power 2 divide by 7 power 4.

Hence required probability=P(A∪B)=P(A)+P(B)=2×3 power 2 into 4 power 2 divide by 7 power 4.