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**essedra** A prize is randomly placed in one of 13 boxes, numbered from 1 to 13.You search for the prize by asking yes-no questions. Find the expected number of questions until you are sure about the location of the prize, under each of the following strategies.

1. An enumeration strategy: you ask questions of the form 'is it in box k'.

(1/13)*1+(12/13)*(1/12)*2+(12/13)*(11/12)*(1/11)*3+...+(12/13)*(11/12)*...*(1/2)*12=(1+2+...+12)/13=6 **but for this answer, it says incorrect. what's wrong about my calculation? **