Problem
A bag contains 4 red marbles, 3 blue marbles, and 5 green marbles. What is the probability of randomly picking a blue marble?
📝Step-by-Step Solution
1
Recall the probability formula
Probability = Number of favorable outcomes / Total number of possible outcomes
P(event) = favorable / total
2
Find the total number of outcomes
Total marbles = 4 red + 3 blue + 5 green = 12 marbles
Total = 4 + 3 + 5 = 12
3
Find the favorable outcomes
We want blue marbles. There are 3 blue marbles.
Favorable = 3
4
Calculate the probability
P(blue) = 3/12 = 1/4
P(blue) = 3/12 = 1/4
5
Express as decimal or percentage (optional)
1/4 = 0.25 = 25%
P(blue) = 0.25 = 25%
✅Final Answer
P(blue) = 1/4 or 25%
Probability ranges from 0 (impossible) to 1 (certain). A probability of 1/4 means if you picked a marble many times (replacing it each time), about 25% of picks would be blue. Always simplify fractions in probability answers.
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