SOLUTION: If the probability that a fluorescent light has a useful life of at least 800 hours is 0.9, find the probabilities that among 20 such lights
(a) exactly 18 will have a useful life
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Question 1137335: If the probability that a fluorescent light has a useful life of at least 800 hours is 0.9, find the probabilities that among 20 such lights
(a) exactly 18 will have a useful life of at least 800 hours;
(b) at least 15 will have a useful life of at least 800 hours
ANS: (a) 0.2852 ; (b)0.9887
Answer by VFBundy(438) (Show Source): You can put this solution on YOUR website!
(a) exactly 18 will have a useful life of at least 800 hours
= 0.2852
(b) at least 15 will have a useful life of at least 800 hours
P(exactly 15 with useful life of at least 800 hours) = = 0.0319
P(exactly 16 with useful life of at least 800 hours) = = 0.0898
P(exactly 17 with useful life of at least 800 hours) = = 0.1901
P(exactly 18 with useful life of at least 800 hours) = = 0.2852
P(exactly 19 with useful life of at least 800 hours) = = 0.2702
P(exactly 20 with useful life of at least 800 hours) = = 0.1216
P(at least 15 will have a useful life of at least 800 hours) = 0.0319 + 0.0898 + 0.1901 + 0.2852 + 0.2702 + 0.1216 = 0.9888
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