某數先減少5%,然後增加5%。若最後所得數是159.6,求該數。
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2007-11-28 12:44 am
回答 (4)
2007-11-28 12:56 am
✔ 最佳答案
設 x 是該數x ( 1-5%) (1 + 5%)= 159.6
x (0.95 ) (1.05) =159.6
x (0.9975) =159.6
x =160 //
2007-11-28 4:10 am
設該數為y.
(95%y)x105%=159.6
95%y=159.6/105%
95%y=167.58
y=167.58/95%
y=159.201
該數是159.201
2007-11-27 20:17:25 補充：
sorry計錯,部計算機有問題
(95%y)x105%=159.6
95%y=159.6/105%
95%y=167.58
y=167.58/95%
y=159.201
該數是159.201
2007-11-27 20:17:25 補充：
sorry計錯,部計算機有問題
2007-11-28 1:13 am
某數先減少5%,然後增加5%。若最後所得數是159.6,求該數。
設該數為y,
y x(1-5%) x (1+5%)=159.6
y x 95% x 105%=159.6
y x 1.05=159.6 /0.95..............將95%化成0.95,105%化成1.05,調 x 0.95過去變/0.95
y=168/1.05..........調 x 1.05過去變/1.05
y=160..................做完啦>>..
設該數為y,
y x(1-5%) x (1+5%)=159.6
y x 95% x 105%=159.6
y x 1.05=159.6 /0.95..............將95%化成0.95,105%化成1.05,調 x 0.95過去變/0.95
y=168/1.05..........調 x 1.05過去變/1.05
y=160..................做完啦>>..
參考: me
2007-11-28 1:06 am
設某數為a
[a x (1 - 5%)] x (1 + 5%) = 159.6
[a x (0.95)] = 159.6 / 1.05
0.95a = 152
a = 160
[a x (1 - 5%)] x (1 + 5%) = 159.6
[a x (0.95)] = 159.6 / 1.05
0.95a = 152
a = 160
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