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Nancy attends her three weekly classes on all three days 80% of the time, two days 15% of the time, one day 4% of the time, and no days 1% of the time. What values does the random variable X take on?
A1, 2, 3, and 4
B0 and 1 only
C0, 1, 2, and 3
D80, 15, 4, and 1
Answer & Solution
Correct answer: C. 0, 1, 2, and 3
1. X is defined as the number of days Nancy attends class in a randomly chosen week.
2. The four described outcomes are attending zero, one, two, or three days.
3. So X takes on the values 0, 1, 2, and 3, matching option A.
4. The percentages 80, 15, 4, and 1 are the probabilities attached to those outcomes, not the outcomes themselves, which rules out option D.
_Source: OpenStax Introductory Statistics (CC BY 4.0), Ch 4 "Discrete Random Variables", section 4.1 Probability Distribution Function (PDF) for a Discrete Random Variable_
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