Question 1191812
a. is the product if they are independent. That is (4/5)(3/4))=3/5
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b. That is (4/5)(1/4)=1/5, the (1/4) is probability B does not last 5 years.
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c. At least one will last 5 years is 1- prob (both don't)
=1-(1/5)(1/4)
=19/20