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Stats help: a certain flight arrives on time 67% of the time.?
a certain flight arrives on time 67% of the time. Suppose 143 flights are randonly selected. Use the normal approximation to the binomial to approximate the probability that:
Exactly 94 flights will be on time
At least 94 flights will be on time
Fewer than 104 will. Be on time
Between 104 and 110 will be on time
Can someone explain the steps, one by one? This is a very difficult class for me and I'm trying very hard to understand. Thanks!
1 Answer
- ?Lv 49 years agoFavorite Answer
n=143 p=0.67
X is approximately Normal with:
mean=np=143*0.67=95.81
variance=np(1-p)=143*0.67*0.33=31.62
so Pr(X<x)=Pr(Z<(x-95.81)/√31.62 )
If you using continuity correction, you have to add or subtract 0.5.
eg. Pr(X=94) is approx: Pr(94-0.5<X<94+0.5) = Pr(93.5<X<94.5)