數學題唔識(急用)

2007-03-14 6:23 am

In a bookshop, the profit made by a calendar is $18. After 2/5 of the calendars are sold, the bookseller reduces the price of each calendar by $10. When all the calendar are sold, the bookseller makes an overall profit of $3000.
(a)Find the total number of calendar he has originally.

更新1:

(b)Suppore the bookseller can only sell a further 100 calendar after the price reduction, and then discard all the remaining calendar.Find the total cost of the calendar if the overall profit percent is 20% 跟上題ga ~~ thx~~^^

更新2:

the answer is $6500,,,but i don't know the example.....

回答 (2)

用戶11400

2007-03-14 8:51 pm

✔ 最佳答案

(a) Let n be the number of calendar he has originally

2/5n * $18 + 3/5n * $(18-10) = $3,000
$7.2n + $4.8n = $3,000
$12n = $3,000
n = 250
He has originally 250 books.

(b)
Remember that over profit percent
= (Total selling price – Total cost) / (Total selling price) * 100%
= Profit / (Profit + total cost) * 100%

(b) Let C be the total cost, and substitute the figures into the above formula while only selling a further 100 calendar after the price reduction, the profit is
(250 * 2/5 * 18 + 100 * 8)/ (250 * 2/5 * 18 + 100 * 8 + C) = 20%
(2,600) / (2,600 + C) = 20%
C = $10,400
The total cost of the calendar is $10,400

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[匿名]

2007-03-14 7:16 am

a) let Y be the total number of calendar he has originally,

18Y*2/5+(18-10)Y*(1-2/5) =3000

then slove it by your calcalator ...

b) let X be the total cost of the calendar if the overall profit percent is 20% ,
{(X+18)*Y*2/5+100*(X+10)}/Y = 20%

And then slove it by your calcalator ...

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