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henrypoo
Mar 11, 2011, 10:16 PM
A coffee powder provider works out the vairable cost of each kg is $2.50 with fixed cost of $30. He sells it to his distributors at $3 per kg. Find the cost function and revenue function if the amount of coffee is produced at x kg.

I'm stuck here! C(x)=30+2.5x
C(x)-2.5=30

Unknown008
Mar 12, 2011, 12:07 AM
C(x)=30+2.5x

This is good, the other one, however, is not. One more thing, it is always good to define what you are writing. What is x here? It's better to say somewhere, "Let x represent the number of kg of coffee.". Then, you say the cost of coffee, C(x) is given by...

This is the cost that the provider has to pay to get the coffee.

Now what is the function that gives the amount of money he gets by selling the coffee? Remember, he sells each kg of coffee at $3 per kg.

Post that, then we will move on to the last part.

henrypoo
Mar 12, 2011, 01:30 AM
Huh. But how to go about finding the function. I'm abit blur about the question. To find c or x

Unknown008
Mar 12, 2011, 02:00 AM
Just find the money he gets for the time being.

Let's say you buy an article for $40 and sell it for $50, what amount of money are you getting back?

Now, let's extent it a little, You buy 200 such items at $40 and sell them for $50 each. How much money are you getting by selling those?

Now, apply the same concept for your problem.

The last step is to find the profit, or loss. But I want you to get the money he receives first.

henrypoo
Mar 12, 2011, 02:05 AM
So he gets $0.50 per kg for selling the coffee?

Unknown008
Mar 12, 2011, 02:23 AM
This isn't what I would understand by that statement...

"He sells it to his distributors at $3 per kg"

henrypoo
Mar 12, 2011, 02:28 AM
Huh what you mean. But the problem is I don't know how much kg he sell. After calculating, he earn $0.50 per kg he sold.

Unknown008
Mar 12, 2011, 02:31 AM
That's why I told you to define your variables first.

"but the problem is i dont know how much kg he sell."

He sold all the coffee he had, that is, he sold x kg of coffee! :)

henrypoo
Mar 12, 2011, 02:38 AM
the variable cost is $2.50 X no of kg which is equal to 2.5x?

henrypoo
Mar 12, 2011, 03:24 AM
Can anyone show me the steps to do it?

Unknown008
Mar 12, 2011, 04:05 AM
Yes, that's the cost, or what you initially called 'Buying price' in small classes. Now I want you to get the 'Selling price'.

henrypoo
Mar 12, 2011, 10:04 PM
The selling price is 3 per kg?

Unknown008
Mar 13, 2011, 02:10 AM
Yes. Now, you already defined the number of kg as being x. What is the total selling price?

henrypoo
Mar 13, 2011, 04:03 AM
3x??

Unknown008
Mar 13, 2011, 04:11 AM
Yes, that's what I was asking you for.

Okay, the cost price is C(x) = 30 + 2.5x

The selling price is S(x) = 3x

Now the profit/loss is how much?

Remember that Profit/loss = Selling Price - Cost Price.

henrypoo
Mar 13, 2011, 04:29 AM
but the cost price is an equation. How to subtract?

Unknown008
Mar 13, 2011, 04:32 AM
Yes, they are both equations, treat them as any normal number, and let's see what happens. Wrap the equation in brackets just you minimise the risk of making mistakes. :)

henrypoo
Mar 13, 2011, 04:41 AM
3x - (Cx=30+2.5x)?

Unknown008
Mar 13, 2011, 04:50 AM
[Notice that revenue is also called selling price ;) ]

Okay, like this:

Selling price - Cost price = Profit/Loss

S(x) - C(x) = Profit/loss

So,

(3x) - (30 + 2.5x) = Profit/Loss

Profit/Loss = (3x) - (30 + 2.5x)

Can you find the function of the profit/loss?

henrypoo
Mar 13, 2011, 05:20 AM
So profit/loss = 5.5x - 30?

Unknown008
Mar 13, 2011, 05:54 AM
No, you didn't take into consideration the brackets.

Profit/Loss = (3x) - (30 + 2.5x) = 3x - 30 - 2.5x

Then you simplify.

henrypoo
Mar 13, 2011, 05:56 AM
5.5x = 30
x = 5.45?

Unknown008
Mar 13, 2011, 06:03 AM
Um.. no.

Profit/Loss = 3x - 2.5x - 30

What is 3x - 2.5x ?

henrypoo
Mar 13, 2011, 06:05 AM
0.5x - 30?
x=60?

Unknown008
Mar 13, 2011, 06:15 AM
Yes, profit/loss = 0.5x - 30

That's it. There is nothing to solve.

What you just got, is the number of kg that the distributor needs to sell to get neither profit nor loss. :)

henrypoo
Mar 13, 2011, 06:28 AM
so the final answer for cost function is C(x) = 30+2.5x and revenue function is 0.5x - 30?

henrypoo
Mar 13, 2011, 06:52 AM
Would you mind reply a little bit faster? Sorry to impose you. But I need to hand in tomorrow

Unknown008
Mar 13, 2011, 06:55 AM
The revenue is simply 3x, as I told you in post #19.

The NET revenue is 0.5x - 30.

Unknown008
Mar 13, 2011, 06:56 AM
would you mind reply a little bit faster? sorry to impose you. but i need to hand in tomorrow

Sorry, I'm doing a lot of work here :(