做不到改修成功率上升，不过能做到长期改修省螺丝
https://i.imgur.com/iF82bnb.png
由图可知
7升8
0.82*0.18*0.18*0.18*0.18≒0.00086
1*0.82+
2*0.82*0.18+
3*0.82*0.18*0.18+
4*0.82*0.18*0.18*0.18+
5*0.82*0.18*0.18*0.18*0.18
≒1.218
确保时螺丝消耗为1.218倍以上从期望值来看你确保就是亏的
8升9
0.77*0.23*0.23*0.23*0.23≒0.002154
1*0.77+
2*0.77*0.23+
3*0.77*0.23*0.23+
4*0.77*0.23*0.23*0.23+
5*0.77*0.23*0.23*0.23*0.23
=1.294≒1.3
确保时螺丝消耗为1.3倍以上你确保就是亏的
9升10
0.67*0.33*0.33*0.33*0.33=0.0079
1*0.67+
2*0.67*0.33+
3*0.67*0.33*0.33+
4*0.67*0.33*0.33*0.33+
5*0.67*0.33*0.33*0.33*0.33
=1.467
确保时螺丝消耗如果是1.467倍以上你确保亏了
材料方面请自己考量价值，我以前拿北方三螺丝当基本单位，图纸不缺后就喜欢用5-5四螺
丝当基本单位haha