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Guest2
 
 

A company wants to spend equal amounts of money for

by Guest2 Sat Sep 06, 2008 8:42 pm

A company wants to spend equal amounts of money for the purchase of two types of computer printers costing $600 and $375 per unit, respectively. What is the fewest number of computer printers that the company can purchase?
(A) 13
(B) 12
(C) 10
(D) 8
(E) 5
divya
 
 

by divya Sat Sep 06, 2008 10:46 pm

A company wants to spend equal amounts of money for the purchase of two types of computer printers costing $600 and $375 per unit, respectively. What is the fewest number of computer printers that the company can purchase?
(A) 13
(B) 12
(C) 10
(D) 8
(E) 5

Is the answer A ?

This is how I approached it :
since equal amounts of money needs to be spent on the 2 type of computer ( $ 600, $ 375)
let x be the number of computer printers for type --A --> $ 600
Let y be the number of computer printers for type --b --> $ 375

600x = 375y

x/y = 375/600
x/y = 5/8

Thus minimally for 5 Type X, for the costs to be equal there has to be 8 type Y
you can also check:
5 * 600 = 3000
8 * 375 = 3000

Thus, total number of computers: 5 + 8 = 13
Guest2
 
 

by Guest2 Mon Sep 08, 2008 8:21 am

The correct answer is A,
Thanks
RonPurewal
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by RonPurewal Mon Sep 29, 2008 5:58 am

the above method is great.

you can also realize that this problem is a thinly veiled way of asking you for the least common multiple of the two prices. in fact, that shouldn't be that hard to see here: you're looking to spend equal amounts of money on the two types of items, so, those equal amounts must be multiples of both prices.
since you're looking for the smallest such multiple, you're looking for the smallest number that's a multiple of both prices - which is the exact definition of the least common multiple.

to find the least common multiple, you could just experiment with numbers, but, if you're looking for a more systematic way, you could use prime factorizations:
600 = 6 x 100 = (2 x 3)(2^2 x 5^2) = 2^3 x 3 x 5^2
375 = 3 x 125 = 3 x 5^3
the least common multiple takes the highest power of every prime number appearing anywhere in these factorizations. therefore, the least common multiple is 2^3 x 3 x 5^3, or 3000.
sachin.w
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Re: A company wants to spend equal amounts of money for

by sachin.w Thu Oct 18, 2012 9:03 pm

I nailed it using the realization that its a LCM question but I don't understand how and why the below works:

600x = 375y

x/y = 375/600
x/y = 5/8

Thus minimally for 5 Type X, for the costs to be equal there has to be 8 type Y
you can also check:
5 * 600 = 3000
8 * 375 = 3000
jnelson0612
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Joined: Fri Feb 05, 2010 10:57 am
 

Re: A company wants to spend equal amounts of money for

by jnelson0612 Fri Oct 19, 2012 10:57 pm

sachin.w Wrote:I nailed it using the realization that its a LCM question but I don't understand how and why the below works:

600x = 375y

x/y = 375/600
x/y = 5/8

Thus minimally for 5 Type X, for the costs to be equal there has to be 8 type Y
you can also check:
5 * 600 = 3000
8 * 375 = 3000


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ManhattanGMAT Instructor