Question 1160213
1.HHH
2.HHT
3.HTH
4.HTT
5.TTT
6.TTH
7.THT
8.THH

No tail = 1/8 
One tail = 3/8
Two tails = 3/8
All tails = 1/8

(1/8×0)+(3/8×5)+(3/8×15)+(1/8×40) = 12.5