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# If x and y are integers, what is the least positive number of 24x+15y?

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Math Revolution GMAT Instructor
Joined: 16 Aug 2015
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GMAT 1: 760 Q51 V42
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If x and y are integers, what is the least positive number of 24x+15y?  [#permalink]

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08 Jun 2016, 17:03
1
6
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Difficulty:

45% (medium)

Question Stats:

64% (01:35) correct 36% (01:31) wrong based on 171 sessions

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If x and y are integers, what is the least positive number of 24x+15y?
A. 1
B. 3
C. 6
D. 9
E. 12

*An answer will be posted in 2 days.

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Re: If x and y are integers, what is the least positive number of 24x+15y?  [#permalink]

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08 Jun 2016, 23:07
3
MathRevolution wrote:
If x and y are integers, what is the least positive number of 24x+15y?
A. 1
B. 3
C. 6
D. 9
E. 12

*An answer will be posted in 2 days.

24x+15y > 0

This means

(take out 3 common) 8x+5y> 0

if 8x = 16, 5y=-15, then we get value as 1.
if 8x = -24, 5y=25, then we get value as 1.

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Re: If x and y are integers, what is the least positive number of 24x+15y?  [#permalink]

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09 Jun 2016, 09:03
1
1
MathRevolution wrote:
If x and y are integers, what is the least positive number of 24x+15y?
A. 1
B. 3
C. 6
D. 9
E. 12

*An answer will be posted in 2 days.

24x+15y > 0

This means

(take out 3 common) 8x+5y> 0

if 8x = 16, 5y=-15, then we get value as 1.
if 8x = -24, 5y=25, then we get value as 1.

By taking 3 common, you have just calculated the minimum positive value for 8x+5y. But the question asks us to calculate the minimum value of 24x+15y, which is 3(8x+5y) = 3*1= 3

So the answer will be B.
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Joined: 04 Feb 2016
Posts: 12
Re: If x and y are integers, what is the least positive number of 24x+15y?  [#permalink]

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09 Jun 2016, 12:40
Anybody actually have a way of solving this w/o plugging in numbers?
Is there a rule or use of prime factors.
Math Revolution GMAT Instructor
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Posts: 8027
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Re: If x and y are integers, what is the least positive number of 24x+15y?  [#permalink]

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10 Jun 2016, 22:55
Since 24(2)-15(3)=3, B is the correct answer.
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Re: If x and y are integers, what is the least positive number of 24x+15y?  [#permalink]

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04 Feb 2018, 00:33
MathRevolution wrote:
If x and y are integers, what is the least positive number of 24x+15y?
A. 1
B. 3
C. 6
D. 9
E. 12

*An answer will be posted in 2 days.

Since 24X + 15Y = X , where X is an Integer with the least value.
So 8X + 5Y = X/3 , where X/3 is an integer

So the question is what is the least value from answers that is divided by 3

Hence, B is the correct answer
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Re: If x and y are integers, what is the least positive number of 24x+15y?  [#permalink]

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04 Feb 2018, 00:40
The equation can be written as 8x + 5y = a/3.. so a can be 3,6,9...
Minimum = 3

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Intern
Joined: 09 Oct 2016
Posts: 32
Re: If x and y are integers, what is the least positive number of 24x+15y?  [#permalink]

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24 Mar 2018, 11:43
1
MathRevolution wrote:
If x and y are integers, what is the least positive number of 24x+15y?
A. 1
B. 3
C. 6
D. 9
E. 12

*An answer will be posted in 2 days.

I took the gmat 2 weeks ago and I got the same question. Luckly I picked B though I was tempting to pick A because I thought I was doing something wrong. I am suprised that this question is on GMATCLUB.
Re: If x and y are integers, what is the least positive number of 24x+15y?   [#permalink] 24 Mar 2018, 11:43
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