The probability that all 4 are teachers is 0.0000135.
The total number is =
4 + 30 + 4
= 38
The committee of 4 from 38 =
38C4 = 73815
The committee of 4 from 4 teachers =
4C4 = 1 way
The total favorable cases = 1 way
Probability = favorability/ total cases
= 1/73815
= 0.0000135
Hence the probability that all 4 are teachers is 0.0000135.
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