Question 1197363
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A focus group of four members is to be randomly selected from an engineer team 
consisting of five engineers and seven technologists.
a) What is the probability that the focus group will be comprised of engineers only?
b) What is the probability that the focus group will be comprised of 2 engineers and 2 technologists?
c) What is the probability that the focus group will have at least 2 technologists?
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<pre>
(a)  P = {{{C[5]^4/C[5+7]^4}}} = {{{C[5]^4/C[12]^4}}} = {{{5/495}}} = {{{1/99}}}.


(b)  P = {{{(C[5]^2*C[7]^2)/C[12]^4}}} = {{{(10*21)/495}}} = {{{210/495}}} = {{{42/99}}}.


(c)  P = {{{(C[7]^2*C[5]^2 + C[7]^3*C[5]^1 + C[7]^4*C[5]^0)/C[12]^4}}} = {{{(21*10 + 35*5 + 35*1)/495}}} = {{{420/495}}} = {{{84/99}}}.
</pre>

Solved.