计算各阈值下的预期净收益

solve()

thr=0.1: 通过率=0.1940, 坏账率=0.0722, 净收益=228.00
thr=0.2: 通过率=0.6360, 坏账率=0.1171, 净收益=618.75
thr=0.3: 通过率=0.8475, 坏账率=0.1611, 净收益=657.00
thr=0.4: 通过率=0.9505, 坏账率=0.1757, 净收益=674.25
thr=0.5: 通过率=0.9910, 坏账率=0.1897, 净收益=640.50
thr=0.6: 通过率=1.0000, 坏账率=0.1910, 净收益=640.50