Hi

 

p and q = .5,  n = 3

 

P( at least one tail) = 1 - P(none) = 1- (.5)^3 = .875 

Answer by drvidmar(5)   (Show Source): You can put this solution on YOUR website!
 a.



There are 8 possible results if you toss the coin three times, all equally likely:  HHH, HHT, HTH, THH, TTH, THT, HTT, and TTT.  In three of those results, you get exactly 2 heads:  HHT, HTH, THH.  Since there are three results with two heads out of eight possible results, the probability is three out of eight, or 3/8, or 37.5%.



b.



Following the same method as in (a), all of the possible results have at least one tail except HHH.  Thus, the the probability of getting at least one tail is seven out of eight, or 7/8, or 87.5%.

 

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