前>>61
>>71
10回1種は6/6^10=1/6^9
10回2種は(5/6)(1/3)^8=5/(2・3^9)
10回3種は(5/6)(2/3)(1/2)^7=5/(2^7・3^2)
10回4種は(5/6)(2/3)(1/2)(2/3)^6=5/3^3=(1/9)(5/3)＞1/9
10回5種は(5/6)(2/3)(1/2)(1/3)(5/6)^5=5^6/(2^6・3^8)=5^6/(9・6^6)=(1/9)(5/6)^6＜1/9
∴4種類