question_answer

A bag contains one marble which is either green or blue, with equal probability. A green marble is put in the bag (so there are 2 marbles now) and then a marble is picked at random from the bag. If the marble taken out is green, then the probability that the remaining marble is also green, is

A)  \[\frac{1}{2}\]     

B)  \[1\]     

C)  \[\frac{2}{3}\]     

D)  \[\frac{1}{3}\]

Correct Answer: B

Solution :

Let G represents green marble and B represents Blue marble. According to the question. After putting a green marble in the bag, we have Let already present marble in the bag is green. Then, after taking green marble. Probability that the remaining marble is also green =1 Let already present marble in the bag is blue, then after taking green marble. Probability that the remaining marble is also green = 0 So, required probability \[=0+1=1\]