3.A computer game software marked at $280 is sold at 20% off.If the discount is 35% of its cost price,find the profit per cent.(ans:40%)
4.A cat and a dog are not satisfied with their weights.If the weight of the cat is increased by 20% while that of the dog is decreased by 10%,their weights will bethe same.What percentage of dog's original weight cat's original weight?(ans:75%)
數學功課問一問 2(急急急急急急急急急)!!!
2007-07-25 10:17 pm
回答 (2)
2007-07-25 10:30 pm
✔ 最佳答案
3. ( $ 280 x 80% - $ 280 x 20 % / 35 % ) / ( $ 280 x 20 % / 35 % )( selling price - cost price ) / cost price
4. A x 120% = B x 90%
A = B x 90% / 120%
A = B x 75 %
( A = cat's weight, B = dog's weight )
參考: myself
2007-07-25 10:32 pm
3.
selling price = $280X(1-20%)= $280 X 0.8=$224
discount=$280-$224=$56
cost price=$56/35%=$56/0.35=$160
profit%=[($224-$160)/$160]X100%=40%
4.
let d kg be dog's original weight and c kg be cat's original weight.
(1+20%)c = (1-10%)d
1.2c = 0.9d
c = 0.75 d
selling price = $280X(1-20%)= $280 X 0.8=$224
discount=$280-$224=$56
cost price=$56/35%=$56/0.35=$160
profit%=[($224-$160)/$160]X100%=40%
4.
let d kg be dog's original weight and c kg be cat's original weight.
(1+20%)c = (1-10%)d
1.2c = 0.9d
c = 0.75 d
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