Accepted Answer

Hi again,

a) The probability of blue is

4/8 =1/2

(ie 1 in 2)

Probability it is white is

1/8

(ie 1 in 8)


b) The probabability of a red first ball is

3/8

The probability of a white second ball is white given that a red was drawn first is

1/7

Note thtat after the first ball is removed that there will only be 7 balls left to pick from hence the 7 instead of the 8

Now we multiply these probability together to get

3/8 x 1/7 = 3/56


c)If we find the probability of the first ball being white and the second ballbeing red then we can just add this to the answer of b) to get the probability of a red and white ball regardless of order drawn.

The probabability of a white first ball is

1/8

The probability of a re second ball is given that a white was drawn first is

3/7

Now we multiply these probability together to get

1/8 x 3/7 = 3/56


So the probability that one ball is red and the other white is

3/56 + 3/56 = 6/56 = 3/28



Please note that these answers could be express as decimals just by working them out on calculator but let as fractions in this question might be tidier.


Again any further question about this question then let me know. All the best,

Ben

Expert:	Ben Brown
Pos. Feedback:	99.4 %
Accepts:	461
Answered:	11/17/2008

Mathematician

First Class Honours in Mathematics from Oxford University