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Margin of Profit
The margin of profit of a company is the net income divided by the total sales.
[1] A company's margin of profit increased by 0.02 from last year.
[2] Last year the company sold its product at $3.00 each and had a net income of $4500.
[3] This year it increased the price of its product by $0.50 each, sold 2000 more,
and had a net income of $7140.
[4] The company never has had a margin of profit greater than 0.15.
How many of its product were sold last year and how many were sold this year?
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I numbered the sentences for easy referring.
Let x be the number of their product that were sold last year.
From [2], we have this expression for margin profit last year
, or . (1)
From [3], we have this expression for margin profit this year
, or (2)
From [1], quantity (2) is 0.02 greater than quantity (1). It gives this equation
- = 0.02.
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| In this problem, the MAJOR STEP is to get a setup equation, |
| and we successfully overcome it (!) |
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+---------------------------------------+
| To solve it is just a brute force. |
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Multiply both sides by x*(x+2000)
2040x - 1500(x + 2000) = 0.02x*(x+2000)
Simplify step by step
2040x - 1500x - 3000000 = 0.02x^2 + 40x
x^2 + 500x - 3000000 = 0
(x-1500)*(x+2000) = 0
So, the rots are 1500 and -2000. We reject the negative root,
and accept the positive one x= 1500.
Thus last year the company sold 1500 units of the product.
This year they sold 2000 units more, i.e. 1500 + 2000 = 3500 units of the product.
Solved.
I'd say it is a good problem of a university Olympiad level for students of Finance department (without any joke).
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Thanks to tutor @math_tutor2020 for correcting me !