Question

There is a box which contains 4 red, 3 blue and 1 black identical balls. For each red ball withdrawn (without replacement), you have to put 1 blue and 1 black ball in the bag. For each blue ball withdrawn (without replacement), you have to put 2 blue and 1 red ball. If the first ball drawn is red, what will be the content of the box just before withdrawing the second ball?

• A. 2 Red, 3 Blue & 1 Black ball
• B. 3 Red, 4 Blue & 2 Black balls
• C. 4 Red, 3 Blue & 2 Black balls
• D. 3 Red, 2 Blue & 1 Black balls.

Answer 1

The correct option is B

3 Red, 4 Blue & 2 Black balls

Box:$$\begin{array}{ccc}\text{4 Red}& \text{3 Blue}& \text{1 Black}\end{array}$$

Step 1: Take out 1 red ball, remaining red balls = 4 - 1 = 3

Step 1: Add 1 blue, total blue balls = 3 + 1 = 4

Step 1: Add 1 Black, total black balls = 1+ 1 = 2

Box: $$\begin{array}{ccc}\text{3 Red}& \text{4 Blue}& \text{2 Black}\end{array}$$
The content of the box after the ${\text{1}}^{st}$ ball is withdrawn is 3 Red, 4 Blue & 2 Black balls.