有D數想問你地

1.
20×(1+r%)=26
10×(1+r%)=13
1+r% = 1.3
r% = 0.3
r = 30

2.
30×(1-r%)=28.2
3×(1-r%)=2.82
1 - r% = 0.94
r% = 0.06
r = 6

3.
d cm×(1 - 35%) = 1.82m
d cm×(1 - 35%) = 182 cm
0.65d = 182
d = 280

1. 若 20x(1+r%)=26 求r
1 + r% = 26 / 20 = 1.3
r% = 1.3 - 1 = 0.3
r/100 = 0.3
r = 0.3 * 100 = 30

2. 若30x(1-r%)=28.2 求r
1 - r% = 28.2 / 30 = 0.94
r% = 1 - 0.94 = 0.06
r/100 = 0.06
r = 0.06 * 100 = 6

3. 水池原來水源d cm 如果水深減少了35% 後 變成了1.82m 求d的值
d * (1 - 35%) = 1.82 * 100 = 182 (留意: 你由m 變成cm, 1 m = 100cm)
d * (1 - 0.35) = 182
d * 0.65 = 182
d = 182 / 0.65 = 280