百分數應用題

合金A(x)
鋅(y)
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x+y=400-------------1
35%x+y=66(1/16)%*(x+y)------------2
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From2:
35%x+y=264.25--------------3
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(1)-(3):
65%x=135.75
x=209(cor to nearest integer)

Put x=209 into 1:
y=191
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合金A(209),鋅(191)

2010-10-24 20:30:51 補充：
.家明把一筆款項存入銀行。若年利率由5%增加至7%,他每年所得的單利息便會增加$500。問家明存入銀行的款項是多少?
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Let P be the principlal:
Px7%x1-Px5%x1=500
2%P=500
P=25000

The principal is $25000.

1.
設 X 為家明存入銀行的款項金額

X*7% - X*5% = 500
X*7/100 - X*5/100 = 500
(7-5)X = 500*100
2X = 50000
X = 50000/2
X = 25000

所以家明存入銀行款項是$25000


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