A bag contains 3 red marbles and 7 blue marbles. You pick a marble, don't replace it, then pick another. What is the probability of picking a red marble first, then a blue marble?
*
3/10
7/10
3/7
7/30
The probability of picking a red marble first is 3/10 because there are 3 red marbles out of a total of 10 marbles.
Since one red marble has already been picked and not replaced, there are now 2 red marbles and 6 blue marbles left. Therefore, the probability of picking a blue marble next is 6/8, which simplifies to 3/4.
To find the probability of both events happening, we multiply the probabilities: (3/10) * (3/4) = 9/40.
Therefore, the probability of picking a red marble first, then a blue marble is 9/40.