Let X= the number of executives with good reading habits: X∼Bin(n,p)
Given p=1/5=0.2,q=1−p=0.8
a.
n=10
P(X=2)=(210)(0.2)2(0.8)10−2=0.301989888 b.
n=20
P(X≥5)=1−P(X=0)−P(X=1)
−P(X=2)−P(X=3)−P(X=4)
1−(020)(0.2)0(0.8)20−0−(120)(0.2)1(0.8)20−1
−(220)(0.2)2(0.8)20−2−(320)(0.2)3(0.8)20−3
−(420)(0.2)4(0.8)20−4=0.3703517361
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