Yeah, but the 10 drops are so rare and hugely affecting the average coins in one drop.
2,3,5,10 average is 5 average and that is not OK. If it is 7 instead of 10 it’d be OK.
I think it is better to go with 4 average.
So if we go with 4 avg then you have seen some 82 Seadragons in 176 runs which gives fantastic 46,6% chance to see the Seadragon.
If we go with 3,3 avg (ignoring the 10 drop completely) then it is 56%.