A bag contains 4 white ball 5 black balls are drawn at random what is ...
Probability of Drawing Same Coloured Balls
Given Information
- 4 white balls
- 5 black balls
Calculation of Probability
There are two possibilities when drawing two balls:
- Both balls are white
- Both balls are black
The probability of drawing two white balls:
P(white ball) = 4/9
P(second white ball) = 3/8 (since there is one less white ball in the bag)
P(both white balls) = (4/9) x (3/8) = 12/72
The probability of drawing two black balls:
P(black ball) = 5/9
P(second black ball) = 4/8 (since there is one less black ball in the bag)
P(both black balls) = (5/9) x (4/8) = 20/72
Total Probability of Same Coloured Balls
The probability of drawing same coloured balls is the sum of the probability of drawing two white balls and the probability of drawing two black balls:
P(same coloured balls) = 12/72 + 20/72 = 32/72 = 4/9
Explanation
The probability of drawing same coloured balls is 4/9. This means that the chances of drawing both white balls or both black balls is 4 out of 9. In other words, if the experiment of drawing two balls is repeated many times, in the long run, we can expect that the same coloured balls will be drawn 4/9 of the time.