Independent solution

How to solve this Independence question

Setup

Setup

Write the husband's survival probability as the complement of his death probability.

Pr(H)=10.10=0.90\Pr(H)=1-0.10=0.90

Model

Model

For independent survival events, the probability that both spouses survive is the product of their marginal survival probabilities.

Pr(HW)=Pr(H)Pr(W)=0.70\Pr(H\cap W)=\Pr(H)\Pr(W)=0.70

Compute

Compute

Recover the wife's survival probability, then take its complement.

Pr(W)=0.700.90=79\Pr(W)=\frac{0.70}{0.90}=\frac79
Pr(Wc)=179=29=0.222222\Pr(W^c)=1-\frac79=\frac29=0.222222\ldots

Answer

Answer

The wife's two-year death probability is approximately 0.222.

0.222(E)\boxed{0.222\quad\text{(E)}}