Answer:
2.86%
Step-by-step explanation:
assuming there is no replacement
There is a total of 6 envelopes
Since the question is asking for red, then green, then red, order is very important
The probability of a red is 3/7
Since we have selected 1 envelope, there are only 6 total envelopes left so the probability of a green is 1/6
Then we need a red again
Since we have selected 2 envelopes, one of which is red, there are only 5 total envelopes and 2 red envelopes so the probability of a red is 2/5
Now we multiply all of these so 3/7x1/6x2/5 = .02857142857
To find the percentage, you multiply by 100 so 2.857142857
Im pretty sure they want you to estimate it so 2.86% is what I would put but it depends on your teacher
