alleryStart learning →In a class, 60 percent are female and 50 percent have long hair. If those two facts were independent, what share would be female with long hair?
A45 percent
B30 percent
C55 percent
D10 percent
Answer & Solution
Correct answer: B. 30 percent
1. For independent events the chance of both is the product of the two chances.
2. Write the two shares as decimals: 0.60 and 0.50.
3. Multiply 0.60 by 0.50.
4. Half of 0.60 is 0.30.
5. So independence would predict 30 percent female with long hair.
6. The class actually has 45 percent, so the two facts are not independent here.
7. Answering 55 percent adds the two shares and halves them, which is not the rule.
8. Answering 10 percent subtracts one share from the other.
_Source: OpenStax High School Statistics (CC BY 4.0), Ch 2 "Descriptive Statistics" and Ch 3 "Probability Topics", section 3.2 Independent and Mutually Exclusive Events_
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