For a probability question about one random pick, first count every item that could be chosen. Then count only the items that match what the question asks for. Put the matching count over the full count. Using another category alone as the denominator compares two categories; it does not give the probability of a pick from the whole group.
Hints
- Hint 1
The sample space is every cookie that could be picked. The bowl has two types, so add their counts to find the total. What expression counts all the cookies?
- Hint 2
A favorable outcome is a pick that matches what the question asks for. The numerator counts those picks, not every cookie in the bowl. Which type of cookie is favorable here?
Step-by-step
Count the target and the whole
Step 1Count every cookie
No Desmos needed. Counting the cookies gives the fraction directly. The sample space is every cookie that could be picked. The two types make up the whole bowl, so add their counts: cookies.
- Step 2
Count the matching cookies
A favorable outcome is a pick that matches the question. The question asks for oatmeal, so cookies are favorable.
- Step 3
Put the matching count over the total
For a random pick, probability is the favorable count divided by the total count. So the probability of choosing oatmeal is
Choice B.