



 
Basma, The most probable number of heads is 13. HOWEVER, this is only the most probable out of 27 different outcomes, and it will happen less than one time in six (about 15.5%). Fourteen or twelve heads are almost equally probable outcomes (about 14.5% of the time). As the imbalance gets greater the probability drops off. So there is no number of heads that "should" occur in the sense that we would be right to be surprised if we dis not see it. RD
 


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