F.3 maths(percentage)~急~

2011-01-15 9:10 pm

A salesman sold two MP4,Sony and Samsung.He made a 20% profit on Sony and a 25% profit on two MP4 together. The cost price of Sony is 40%higher than that of Samsung.

(a)Find the percentage profit on Samsung.

(b)If the selling price of Samsung is $2970,find the total profit.

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回答 (1)

用戶10012

2011-01-15 9:43 pm

✔ 最佳答案

Let cost of Samsung = c, so cost of Sony = 1.4c.
Selling price of Sony = 1.4c(1 + 20%) = (1.4c)(1.2) = 1.68c.
Let % profit of Samsung = p
So selling price of Samsung = c(1 + p)
Total cost = c + 1.4c = 2.4c
Total selling price = 1.68c + c(1 + p)
So % profit = {[1.68c + c(1 + p)] - 2.4c}/2.4c x 100% = 25%
(1.68c + c + cp - 2.4c)/2.4c = 25/100 = 0.25
1.68c + c + cp - 2.4c = (0.25)(2.4c) = 0.6c
0.28c + cp = 0.6c
0.28 + p = 0.6
p = 0.6 - 0.28 = 0.32 = 32%.
(b) 2970 = c(1 + 32%) = 1.32c, so c = 2250
So total cost = 2.4c = 5400
Total selling price = 1.68(2250) + 2970 = 6750
So total profit = 6750 - 5400 = 1350

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