Question
The probability that a family owns a laptop is 0.68; that it also owns a desktop is 0.56. If the probability that it owns both is 0.48, then what is the probability that a randomly selected family owns a laptop or a desktop?
NDA
Mathematics
Probability
2025
NDA 2025 (Phase 2)
NDA Mathematics Question (2025) — Solution
Options
- A. 0.80
- B. 0.76
- C. 0.36
- D. 0.28
Answer
B. 0.76
Step-by-step solution
Let L be the event that a family owns a laptop and D be the event that a family owns a desktop. Given: P(L) = 0.68 P(D) = 0.56 P(L D) = 0.48 The probability that a randomly selected family owns a laptop or a desktop is given by P(L D). Using the addition theorem of probability: P(L D) = P(L) + P(D) - P(L D) Substituting the given values: P(L D) = 0.68 + 0.56 - 0.48 P(L D) = 1.24 - 0.48 = 0.76
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