Answer:
20%
Explanation:
Let's break this down into simpler terms.
We know that:
There are 15 total cookies.
7 of them are chocolate chip.
Therefore, the ratio of chocolate chip cookies to total cookies is 7:15.
In other words, there is a 7 out of 15 chance that you will pick a chocolate chip cookie the first time. This percentage is 46.666666666667%.
Now, we have to figure out the percentage after you eat it. The new ratio of chocolate chip cookies to total cookies is 6:14.
In other words, there is a 6 out of 14 chance that you will pick a chocolate chip cookie the second time. This percentage is 42.857142857143%.
Now, we have to combine the two, as the second percentage only happens if the first percentage works (if that makes any sense).
Surprisingly, 42.857142857143% of 46.666666666667% rounds to exactly 0.2, which written as a percent is 20%.
Therefore, there is a 20% chance that you will choose a chocolate chip cookie, eat it, and then choose another chocolate chip cookie.