有關percentage既幾條問題

汀=)

2009-11-29 9:35 pm

1) if A is 50% greater than B, then what percentage of A+B is A - B?
2) if x is 60% more than y, by what percentage is y less than x?
3) the cost price of a toy is $180. When the toy is sold at a discount of 10%, the
profit per cent is 25%. What is the marked price of the toy?
4) in a department store, 70% of a product are sold at a profit of 40% and the
rest are sold at a loss of 15%. What is the profit per cent if every single piece
of the product has been sold? (assume that the cost price of the product is a constant)
5) the value of a machine depreciates by 30% in the first year and by 20% in
each subsequent year. if its value becomes $14336 after 5 years, what was its
original value?

請列steps!! thanks!

回答 (1)

用戶9112

2009-11-30 4:58 am

✔ 最佳答案

1) A = (1 + 50%)B = 1.5B
(A - B)/(A + B) * 100%
= (1.5B - B)/(1.5B + B) * 100%
= 0.5B / 2.5B * 100%
= 20%
2) x = (1 + 60%)y = 1.6y
y is less than x by (x - y)/y * 100%
= (1.6y - y)/1.6y * 100%
= 0.6y/1.6y * 100%
= 37.5%
3) The sales price = $180 * (1 + 25%)
= $180 * 1.25
= $225
The marked price = $225 / (1 - 10%)
= $225 / 0.9
= $250
4) Let the cost price of all items be $x
Revenue for the product with profit = $x * 70% * (1 + 40%)
= $x * 0.7 * 1.4
= $0.98x
Revenue for the product with loss = $x * 30% * (1 - 15%)
= $x * 0.3 * 0.85
= $0.255x
Total revenue = 0.98x + 0.255x = $1.235x
Profit percent = (1.235x - x)/x * 100% = 23.5%
5) Let the original value be $x
The value after 5 years = $x * (1 - 30%) * (1 - 20%)^4 = $14336
(x)(0.7)(0.8^4) = 14336
0.28672x = 14336
x = 50000
The original value is $50000

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