Answer:
k = 10
Explanation:
The initial polynomial is:

If f(-2) = 0, then when we replace x by -2, the result will be 0. It means that we can write the following equation:

Therefore, we can solve for k as follows:

So, the value of k is 10
Yellow: 25.71% chance of you grabbing a yellow jelly bean
Green:34.29% chance of you grabbing a green jelly bean
Red: 40% chance of you grabbing a red jelly bean