Answer:
1/7
Explanation:
6 + 5 + 4 = 15
There are 15 marbles to start with.
p(event) = (number of desired outcomes)/(total number of outcomes)
First pick (there are 6 desired outcomes out of a total of 15 possible outcomes):
p(r) = 6/15
Now there are 5 red marbles left and a total of 14 marbles left.
Second pick (there are 5 desired outcomes out of a total of 14 possible outcomes):
p(r) = 5/14
These events are independent, so we multiply the two probabilities.
p(r, r) = 6/15 × 5/14
p(r, r) = 3/7 × 1/3
p(r, r) = 1/7