Question 1138787
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The number of all different samples of 3 tomatoes from 9 tomatoes is  {{{C[9]^3}}} = {{{(9*8*7)/(1*2*3)}}} = 84.


It is your space of samples.


The number of triples containing one rotten tomato is  {{{C[8]^2}}} = {{{(8*7)/(1*2)}}} = 28.


      It is the number of pairs of tomatoes what you can add from remaining 9-1 = 8 tomatoes to this one rotten.



So the probability under the question is  {{{28/84}}} = {{{1/3}}}.   <U>ANSWER</U>
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