
Dibyendu D. answered 12/08/19
More than 2 years of experience in teaching SAT/ACT/GRE/GMAT Math
If each boy is eligible for all the prizes, the 1st prize can be given away to any one of the boys and thus it can be given away in 3 different ways.
Similarly, the 2nd prize can be given away to any one of them in 3 different ways again and so on.
Hence, the total number of way all 4 prizes can be given away is 3*3*3*3 = 34 = 81