Question 1160746
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It is the binomial type probability distribution.


The number of trial n= 7; the probability of the success trial is  0.25,  and the number of success trial k = 3. 


    P = {{{C[7]^3*0.25^3*(1-0.25)^4}}} = {{{((7*6*5)/(1*2*3))*0.25^3*0.75^4}}} = 0.173035.     <U>ANSWER</U>
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Solved.