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The probabilities that a man and his wife live for 80 years ...

The probabilities that a man and his wife live for 80 years are 23 and 35 respectively. Find the probability that at least one of them will live up to 80 years

A.

215

B.

315

C.

715

D.

1315

Correct answer is D

Man lives = 23 not live = 13

Wife lives = 35 not live = 25

P(at least one lives to 80 years) = P(man lives to 80 not woman) + P(woman lives to 80 and not man) + P(both live to 80)

P=(23×25)+(25×13)+(23×35)

= 415+315+615

= 1315