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### Show Tags

06 Apr 2011, 10:09
3
00:00

Difficulty:

55% (hard)

Question Stats:

63% (01:56) correct 37% (02:13) wrong based on 99 sessions

### HideShow timer Statistics

John buys koolaid for 12$at a local store. If he bought it at the wholesale store he would get an extra liter of koolaid for the same cost. Also the koolaid is 1$ cheaper per liter at the wholesale store. what is the price per liter of the koolaid at the local store

A. 3
B. 4
C. 5
D. 6
E. 7
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Posts: 1795
Re: John buys koolaid for 12$at a local store. If he bought it at the who [#permalink] ### Show Tags 06 Apr 2011, 10:36 rxs0005 wrote: John buys koolaid for 12$ at a local store. If he bought it at the wholesale store he would get an extra liter of koolaid for the same cost. Also the koolaid is 1$cheaper per liter at the wholesale store. what is the price per liter of the koolaid at the local store 3 4 5 6 7 Let's say John bought x litres of koolaid from the local store. x liters->$12
1 liter -> 12/x

Wholesale store:
(x+1) liters -> $12 1 liter -> 12/(x+1) 12/(x+1) is$1 less than 12/x

$$\frac{12}{x+1}+1=\frac{12}{x}$$

$$\frac{13+x}{x+1}=\frac{12}{x}$$

$$13x+x^2=12x+12$$
$$x^2+x-12=0$$
$$x^2+4x-3x-12=0$$
$$x(x+4)-3(x+4)=0$$
$$(x-3)(x+4)=0$$

$$x=3 \hspace{2} OR \hspace{2} x=-4$$
Quantity of koolaid can't be negative.
$$x=3$$
John bought 3 liters of koolaid from the local store for $12 Price per liter = 12/x = 12/3 =$4

Ans: "B"
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### Show Tags

06 Apr 2011, 11:40
i love the number 12. whenevr there is a question on factors and equality-3 or 4 is the correct answer most of the times. other examples talk abt cost of one being 25% more/less etc.

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### Show Tags

06 Apr 2011, 19:50
12/(x+1) = 12/x -1

=>x = -4 or 3

=> x = 3 as price cannot be negative.

=> price per liter at local store = 12/3 = 4

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03 Dec 2017, 21:28
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