# [URGENT HELP] maths problem

• Jul 6th 2009, 03:18 AM
erarkku
[URGENT HELP] maths problem
heyy people of maths help forum i'm facing troubles of my own solving this question

a manufacture makes hi-fi systems and sells it to the wholesaler for 15% + cost of making , the wholesaler then sells it to the retailer at price + 20%, then the retailer sells to ME at $1470 including 30% of it is profit for the retailer. find the cost of making the hi-fi system whopss forgot to add that sorry. • Jul 6th 2009, 04:07 AM Swlabr Quote: Originally Posted by erarkku heyy people of maths help forum i'm facing troubles of my own solving this question a manufacture makes hi-fi systems and sells it to the wholesaler for 15% + cost of making , the wholesaler then sells it to the retailer at price + 20%, then the retailer sells to ME at$1470 including 30% of it is profit for the retailer.

find the cost of making the hi-fi system whopss forgot to add that sorry.

The "trick" to these questions is make them into equations.

Let $\displaystyle x$ be the cost of making the system. So,

the wholesaler bought it for $\displaystyle y=x + (15$% $\displaystyle \text{of } x) = x + 0.15x=1.15x$,

the retailer bought it for $\displaystyle z=1.20y$,

and you bought it for $\displaystyle 1470=1.30z$.

Now, substitute everything into the last equation. $\displaystyle 1470=1.30z=1.30*(1.20y)= \ldots$, and then you will have an equation that is only in terms of $\displaystyle x$, which is what you wish to find. So, just solve for $\displaystyle x$.
• Jul 6th 2009, 12:40 PM
Sooda
Solving this problem like Swlabr suggested seems professional way. Though I prefer step by step explanations and answers, that way I can examine and learn more.
Math should be logical (that is why I registered here -- to learn). I have finished high school in USA terms and have idea how to get answer.

I am going to subtract percentages until I get manufacturer production cost, it should be possible.

30% from 1470 is 1470 * 0.3 = 441, Retailer got it for 1470 - 441 = 1029
20% from 1029 is 1029 * 0.2 = 205.8,Wholesaler got it for 1029 - 205.8 = 823.2
15% from 823.2 is 823.2 * 0.15 = 123.48, Manufacturer production cost was 823.2 - 123.48 = 699.72 ($) Hi-fi system costs 699.72$.

I am learning by doing.
• Jul 8th 2009, 01:08 AM
Swlabr
Quote:

Originally Posted by Sooda
Solving this problem like Swlabr suggested seems professional way. Though I prefer step by step explanations and answers, that way I can examine and learn more.
Math should be logical (that is why I registered here -- to learn). I have finished high school in USA terms and have idea how to get answer.

I am going to subtract percentages until I get manufacturer production cost, it should be possible.

30% from 1470 is 1470 * 0.3 = 441, Retailer got it for 1470 - 441 = 1029
20% from 1029 is 1029 * 0.2 = 205.8,Wholesaler got it for 1029 - 205.8 = 823.2
15% from 823.2 is 823.2 * 0.15 = 123.48, Manufacturer production cost was 823.2 - 123.48 = 699.72 ($) Hi-fi system costs 699.72$.

I am learning by doing.

Hi, I appologise for my delay in replying.

However, I would like to point out that your answer is actually incorrect. You said:
Quote:

Originally Posted by Sooda
30% from 1470 is 1470 * 0.3 = 441, Retailer got it for 1470 - 441 = 1029

and so on. What you are doing here is finding 30% of the final cost, not of the initial cost. These are different. To put it in equations:

$\displaystyle 1470 * 0.3 = 441 \neq 1029*0.3$, where $\displaystyle 1029*0.3$ would be the profit from that stage if they had bought it for 1029.

I hope that makes sense.

Basically, your problem is that you are finding the percentages of the final price not of the price that the seller, maker, etc bought it for, and these percentages are different.

The final answer is, I believe, £819.40 by rounding.
• Jul 8th 2009, 02:36 AM
Swlabr
Quote:

Originally Posted by Stroodle
You need to make your spam a bit shorter. No-one's gonna read that chunk of text...

I don't think your meant to read it, just click the links. His other posts are the same (see the Geometry forum), just with different issues being discussed.