Alan collects data about the students in his class. He records their hair color and whether they have freckles. His results are shown in the table below.
Category Brown Hair Blonde Hair Red Hair
Freckles 4 5 4
No Freckles 7 4 1
Find each probability.
P(freckles)
P(blonde hair or red hair)
P(freckles and brown hair)
P(no freckles|red hair)
To find the probabilities, we need to divide the desired outcomes by the total number of outcomes.
Total number of students = 4 + 5 + 4 + 7 + 4 + 1 = 25
1. P(freckles) = (4 + 5 + 4) / 25 = 13 / 25 = 0.52 or 52%
2. P(blonde hair or red hair) = (5 + 4 + 1) / 25 = 10 / 25 = 0.40 or 40%
3. P(freckles and brown hair) = 4 / 25 = 0.16 or 16%
4. P(no freckles|red hair) = 1 / 10 = 0.10 or 10%