A random pick from a table of counts calls for probability: the number of matching outcomes divided by the number of possible outcomes. Read the requested row for the top of the fraction, then add every row for the bottom; Desmos can total the rows. The tempting slip is to count a different color or leave one out of the whole jar.
Hints
- Hint 1
In a probability fraction, the top counts the outcomes that match the question. A token matches only if it is blue. Which row of the table gives that count?
- Hint 2
The bottom counts every token that could be picked, called the sample space. The selection is from the whole jar, so add the red, blue, and green counts.
Step-by-step
Count blue tokens over all tokens
Step 1Identify the matching tokens
The question asks for blue, so the Blue row's tokens are the favorable outcomes, the picks that match what you want.
- Step 2
Count every possible pick
The token is selected from the whole jar, so the sample space, or set of possible picks, includes all three colors. Type in Desmos; it shows tokens in all.
- Step 3
Write the probability
For a random pick, probability is the matching count over the whole count:
So the probability of picking a blue token is . Choice B.