Problem-Solving and Data AnalysisMediumProbability of the complement
Problem-Solving and Data Analysis practice question
The probability that a certain flight departs on time is 0.35. What is the probability that the flight does NOT depart on time?
- A. 0.65Correct
- B. 0.35
- C. 0.45
- D. 1.35
Answer: A. 0.65
An event and its opposite together account for everything, so their probabilities add to 1. The probability of not departing on time is 1 − 0.35 = 0.65.
Why the other answers are wrong
- B. 0.35
- 0.35 is the probability the flight DOES depart on time. The question asks for the opposite event.
- C. 0.45
- 0.45 would be 1 − 0.55. The given probability is 0.35, and 1 − 0.35 = 0.65.
- D. 1.35
- 1.35 is 1 + 0.35. No probability can exceed 1. The complement is found by subtracting from 1.
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