Question 1114903
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Your formulation of the given part is incorrect (which demonstrates that you do not understand what you are posting for . . . (unfortunately) )


The correct formulation of the given part is THIS:


<pre>
    The probability of a man to live 20 more years is X and the probability of his wife to live 20 more years is Y.
</pre>


The partial answers are:


<pre>
1)  1 - (1-X)*(1-Y) = X + Y - XY.


2)  X*(1-Y) + Y*(1-X) = X + Y - 2*XY.


3)  X*(1-Y).
</pre>

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This problem was posted to the forum, probably, one year ago.


See the link

<A = HREF=https://www.algebra.com/algebra/homework/Probability-and-statistics/Probability-and-statistics.faq.question.1105633.html>https://www.algebra.com/algebra/homework/Probability-and-statistics/Probability-and-statistics.faq.question.1105633.html</A>


https://www.algebra.com/algebra/homework/Probability-and-statistics/Probability-and-statistics.faq.question.1105633.html



and my solution there.