What is the probability of getting 60% or better on a true false exam with 50 questions
1 answer:
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Answer:
a) P(X>np+3=0.017
b) P(x>1)=0.190
c) P(Y>1)=0.651
Step-by-step explanation:
This a binomial experiment where success is denoted by parts that need rework.
X ∼ B(n, p); n = 20; p = 0.01
The expected value of X is: E(X) = np =20×0.01= 0.2
The variance is: Var(X) = np(1 − p) = 0.2 × 0.99 = 0.198,
The standard deviation SD(X)= ≈ 0.445
a) P(X>np+3=P(X>0.2+3×0.445)=P(X>1.535)=P(X≥2)
Probability function is given by:
P(X≥2)=1-P(X<2)=1-P(X=1)-P(X=0)= 1 - -
P(X≥2)=1-0.165-0.818=0.017
b) p=0.04
P(x>1)=P(x≥2)= 1 - P(x=1) - P(x=0)= 1 - -
P(x>1)= 1 - 0.368 - 0.442=0.190
c) In this case we consider p=0.19 (Probability that X exceeds 1)
In this experiment Y is the number of hours and n= 5 hours.
Then, we check the probability in each hour:
P(Y>1)=1- P(Y=0)
P(Y=0)==0.349
P(Y>1)=1-0.349=0.651