please explain question B PLEASE SHOW WORK TO GET FULL CREDT Problem 2) The life
ID: 3359884 • Letter: P
Question
please explain question B
Explanation / Answer
(b) If 4 lasers are randomly selected.
All are random and independent lasers
Here mean life length of an laser is = 7000 hours
Here Pr(any random laser will exceed 7000 hours) = 0.5
as the probability on either side of mean is 0.5
so Now this question will behave like a binomial distribution where n = 4 and p= 0.5
now we have to find that at least one of these 4 lasers have life length above 7000 hours
so Pr(X > 0) = BIN (X >0 ; 4 ; 0.5) = 1 - BIN (X = 0; 4 ; 0.5)
where X is the number of lasers whose life length exceeds 7000 hours.
Pr(X > 0) = BIN (X >0 ; 4 ; 0.5) = 1 - BIN (X = 0; 4 ; 0.5) = 1- 0.54 = 0.9375
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