Let a fair die be rolled n times. Let’s make an assumption that all rolls of a die are independent. If x and y are the outcomes of any two of n trials, what is the distribution function of XY
1×1=1 1×2=2 1×3=3 1×4=4 1×5=5 1×6=6
2×1=2 2×2=4 2×3=6 2×4=8 2×5=10 2×6=12
3×1=3 3×2=6 3×3=9 3×4=12 3×5=15 3×6=18
4×1=4 4×2=8 4×3=12 4×4=16 4×5=20 4×6=24
5×1=5 5×2=10 5×3=15 5×4=20 5×5=25 5×6=30
6×1=6 6×2=12 6×3=18 6×4=24 6×5=30 6×6=36
The products are 1,2,3,4,5,6,8,9,10,12,15,16,18,20,24,25,30,36
XY no. of ways P(xy)
1 1 1/36
2 2 2/36
3 2 2/36
4 3 3/36
5 2 2/36
6 4 4/36
8 2 2/36
9 1 1/36
10 2 2/36
12 4 4/36
15 2 2/36
16 1 1/36
18 2 2/36
20 2 2/36
24 2 2/36
25 1 1/36
30 2 2/36
36 1 1/36
Edwin