577 views
1 votes
1 votes

QUESTION 8 : A bag contains 5 balls out of which some or maybe all are black. 2 balls are drawn from the bag and both are found to be black. What is the probability that all balls in the bag are black?

5 Answers

0 votes
0 votes
2 balls are drawn from the bag and both are found to be black that means we have to find out the probability of 3 balls to be black
So, (1/2)*(1/2)*(1/2) = 1 / 8
0 votes
0 votes
As three balls are left in the bag, we first draw the third ball & check for its colour & so on.

Probability of all balls to be black is given by

p(b)=p(third)*p(fourth)*p(fifth)

      =((1/3)*1/2)) * ((1/2)*(1/2)) * ((1)*(1/2))

      =1/48
0 votes
0 votes

I think ans should be 1/4

Given than 2 balls are black,sample space  for all other balls(N= Non black B=Black)

{NNN,BNN,BBN,BBB}

Here we can see chance of getting all black balls are 1/4

Related questions

1 votes
1 votes
1 answer
1
Indranil Pradhan asked Jun 5, 2019
290 views
An element is to be inserted in an array and the probability that it has been entered correctly is 0.9. Find the probability that the sorting algorithm worked correctly.H...
0 votes
0 votes
1 answer
3
adarsh shivhare asked Aug 12, 2018
948 views
A deck of 52 playing cards is shuffled, and the cards are turned up one at a time until the first ace appears. Is the next card—that is, the card following the first ac...
0 votes
0 votes
2 answers
4