



 
Sueheir, If there was only one question then there would be 3 possible answers
Now add a second question. Anyone taking the survey could answer the second question G, A or P regardless of how they answered the first question. Thus for a two question server there are 3 3 = 3^{2} = 9 possible answers
Now add a third question. Any of the possible two question responses above can be extended to a three question response by appending a G, A or P. Thus there are 3^{3} = 27 possible combination to a three question survey. You should be able to complete it now.  


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