該公司應把標價再提百分之幾,方能有8% 的盈利率 ?

假設要提高之百分比為 "Z"

來價=A; 正常標價 = 1.2A

1.2A x (1 + Z) x 0.75 = 1.08A
0.9A x (1+Z) = 1.08A
0.9 x (1+Z) = 1.08
1+ Z = 1.2
Z = 0.2

So, 要高之百分比為 20%

假設貨品來價 (成本)是100, 及設該公司應把標價再提高 y%

100 x (1+20%) x (1+y%) x 75% = 100 x (1+8%)
120 x (1+y%) x 0.75 = 108
90 x (1+y%) = 108
1+y% = 1.2
y% = 0.2
y = 20

所以, 該公司應把標價再提高20%