Two balls are drawn from a bag containing 5 white and 7 black balls at random. What is the probability that they would be of different colours?
2 Answers
Explanation:
#"assuming replacement of the first ball"#
#P("white")=5/12#
#P("white and black")#
#=5/12xx7/12=35/144#
#P("black and white")#
#=7/12 xx5/12 = 35/144#
If the first ball is replaced:
If the first ball is not replaced:
Explanation:
There are
- both are white
- both are black
- one of each color
The probability of one of each color is
If the first ball is replaced:
However, if the first ball is NOT replaced, the probability changes for the second ball. There are fewer of one color and one ball less.