# Cheating in Exam

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• Published : October 23, 2012

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3. a) What is the probability that none of these vehicles requires warranty service? -------------------------------------------------
P(x=0) = 12 C0 (0.10)0 (1-0.10)12-0
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= (1) (1) (0.28243)
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=0.28243
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b) What is the probability that exactly nine of these vehicles require warranty service? -------------------------------------------------
P(x=9) = 12 C9 (0.10)9 (1-0.10)12-9
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= (220) (0.000000001) (0.729)
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=0.00000022 X 0.729
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=0.000000016038
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c) What is the probability that greater than nine of these vehicles require warranty service? -------------------------------------------------
P (x > 9) = p (x= 9), p (x=10), p (x =11), p (x = 12).
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= 12 C9 (0.10)9 (1-0.10)12-9+12 C10 (0.10) 10 (1-0.10)12-10+ 12 C11 (0.10) 11 (1-0.10)12-11+ 12 C12 (0.10)12 (1-0.10)12-12 -------------------------------------------------
=0.000000016038+0.000000005346+0.000000000108+0.000000000001 -------------------------------------------------
=0.000000021493
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d) What is the probability that three and fewer of these vehicles requires warranty service? -------------------------------------------------
P (x≤ = 3) =p (x =3), P(x= 2), p (x=1), p (x = 0)
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12 C3 (0.10)3 (0.9)9+12 C2 (0.10)2(0.9)10 + 12 C1 (0.10)1 (0.9)11 + 12 C0 (0.10)0 (0.9)12 -------------------------------------------------
=0.08523+0.2301+0.3766+0.282
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= 0.97433
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E) What is the mean and variance for these vehicles?
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The mean= (nπ)
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=12(0.1)
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=1.2
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Variance π (1-π)
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= (12) (0.1) (0.9)
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=1.08
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4 a) what percent of the adults spend more than RM 2500 per year on reading and entertainment? -------------------------------------------------
P (x)> 2500= p (z > (2500 – 1994) =506) =1.12=0.3686 =0.5 – 0.3686 =0.1314 -------------------------------------------------
450 450
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b) What percent of the adults spend more than RM 2500 per year on reading and entertainment? -------------------------------------------------
P (2500 -1994) < z < 3000-1994)
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450450
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=p (1.12 < z < 2.24)
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=0.4875-0.3686
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=0.1189
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1.12 2.24
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c) What percent of the adults spend more than RM 3000 per year on reading and entertainment?...