Question 930943: it is known that 80% of all college professors have doctoral degree. if 10 professors are randomly selected find the probability that
a: fewer than 4 have doctoral degree
b: at least 6 have doctoral degree
c: between 5 and 7 (inclusive) have doctoral degree
please help me to understand it step by step .Thank u :)
Answer by ewatrrr(24785)   (Show Source):
You can put this solution on YOUR website! n(doc degree) = .80 , n = 10
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Using a TI calculator 0r similarly a Casio fx-115 ES plus
P(x < 4)= binomcdf(10, .80, 3) = .00086
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P(x ≥ 6) = 1 - binomcdf(10, .80, 5)= 1-.0328 = .9672
..........
P(5≤ x ≤ 7) = binomcdf(10, .80, 7) - [ 1- binomcdf(10, .80, 4)]
P(5≤ x ≤ 7) = .3222 - .0064 = .3158
0r
P(5≤ x ≤ 7) = P(x=5) + P(x=6) + P(x=7) = .0264 + .0881 + .2013 = .3158
Using binompdf() Or for ex P(x=5) = 10C5(.8)^5(.2)^5
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