Asked by Alice
A bottle contains 12 red marbles and 8 blue marbles. A marble is chosen at random and not replaced. Then, a second marble is chosen at random. Determine the probability that the two marbles are not the same color. Determine the probability that at least one of the marbles is red.
Answers
Answered by
oobleck
20 marbles in all
P1(red,blue) = 12/20 * 8/19
P2(blue,red) = 8/20 * 12/19
so, P(different) = P1+P2 = 48/95
Note that
P1(red,red) = 12/20 * 11/19
P2(blue,blue) = 8/20 * 7/19
P(not same) = 1 - (P1+P2) = 48/95
P(at least 1 red) = 1 - P(blue,blue) = 81/95
Check to see that this is also P(not same) + P(red,red)
P1(red,blue) = 12/20 * 8/19
P2(blue,red) = 8/20 * 12/19
so, P(different) = P1+P2 = 48/95
Note that
P1(red,red) = 12/20 * 11/19
P2(blue,blue) = 8/20 * 7/19
P(not same) = 1 - (P1+P2) = 48/95
P(at least 1 red) = 1 - P(blue,blue) = 81/95
Check to see that this is also P(not same) + P(red,red)
There are no AI answers yet. The ability to request AI answers is coming soon!
Submit Your Answer
We prioritize human answers over AI answers.
If you are human, and you can answer this question, please submit your answer.