Question 23
ProbabilityThe probabilities that a husband and wife will be alive in 15 years' time are m and n respectively. Find the probability that only one of them will be alive at that time.
- A.mn
- B.m + n
- C.m + n − 2mn
- D.1 − mn
Show the answer and explanation
Answer: C (m + n − 2mn)
Explanation
Only one alive = husband alive and wife not, or wife alive and husband not: m(1 − n) + n(1 − m) = m + n − 2mn.