做不到改修成功率上升，不過能做到長期改修省螺絲
https://i.imgur.com/iF82bnb.png
由圖可知
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
確保時螺絲消耗為1.218倍以上從期望值來看你確保就是虧的
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
確保時螺絲消耗為1.3倍以上你確保就是虧的
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
確保時螺絲消耗如果是1.467倍以上你確保虧了
材料方面請自己考量價值，我以前拿北方三螺絲當基本單位，圖紙不缺後就喜歡用5-5四螺
絲當基本單位haha