If x + y + z + w = 15, then at least k of the numbers x, y, z, w must be positive, where k is : Choices
A) 0	B) 1	C) 2	D) 3	E) 4
straight forward 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.   ANSWER:1
<result>B</result>
If x + y + z + w = 15, then at least k of the numbers x, y, z, w must be positive, where k is :