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If x + y + z + w = 15, then at least k of the numbers x, y, z, w must
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Updated on: 06 Jan 2016, 07:42
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If x + y + z + w = 15, then at least k of the numbers x, y, z, w must be positive, where k is : (A) 0 (B) 1 (C) 2 (D) 3 (E) 4
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Originally posted by sara86 on 06 Jan 2016, 07:37.
Last edited by Bunuel on 06 Jan 2016, 07:42, edited 1 time in total.
Renamed the topic, edited the question and added the OA.



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Re: If x + y + z + w = 15, then at least k of the numbers x, y, z, w must
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06 Jan 2016, 07:45
sara86 wrote: If x + y + z + w = 15, then at least k of the numbers x, y, z, w must be positive, where k is :
(A) 0
(B) 1
(C) 2
(D) 3
(E) 4 Straightforward question if you realize that 4 negative numbers when added can NEVER give you a positive sum. This directly eliminates A. As we are given that x+y+z+w=15 and we need to find what is the least number of variables out of the 4 given (x,y,z,w) that need to be positive to adhere to x+y+z+w=15 , Consider any large value for x = 45 and 15,10 and 5 for y,z,w respectively to give you x+y+z+w=15. Thus k =1 for 'k' value to be the least. Hope this helps.



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Re: If x + y + z + w = 15, then at least k of the numbers x, y, z, w must
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06 Jan 2016, 19:40
sara86 wrote: If x + y + z + w = 15, then at least k of the numbers x, y, z, w must be positive, where k is :
(A) 0
(B) 1
(C) 2
(D) 3
(E) 4 If we say that none of the numbers are positive, then the sam cannot be positive. (Keep in mind that question is asking positive, not nonnegative. 0 is not positive) Hence Option A is out. If you want the sum of 4 numbers to be always positive, you can do that by making one number very large and the rest of numbers and small negative numbers. Ofcourse, more than 1 positive large numbers will also yield the same result. But since we are asked about the least number of positive numbers, it should be 1. Option B



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Re: If x + y + z + w = 15, then at least k of the numbers x, y, z, w must
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30 Jul 2016, 18:25
Hi! I don´t understand the concept "at least k of the numbers" what does it mean? Even though, I´ve got it correct. I thought "k" was multiplying the variables?
Thanks a lot.



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Re: If x + y + z + w = 15, then at least k of the numbers x, y, z, w must
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03 Oct 2018, 09:16
Bruma14 wrote: Hi! I don´t understand the concept "at least k of the numbers" what does it mean? Even though, I´ve got it correct. I thought "k" was multiplying the variables?
Thanks a lot. At least K means we are referring to the least value of K. Now for the sum to be positive at least one of these number must be positive. Hence 1




Re: If x + y + z + w = 15, then at least k of the numbers x, y, z, w must &nbs
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03 Oct 2018, 09:16






