Each of the integers from 0 to 9, inclusive, is written on a separate slip of blank paper and the ten slips are dropped into hat. If the slips are then drawn one at a time without replacement, how many must be drawn to ensure that the numbers on two of the slips drawn will have a sum of 12? Choices:
A) 6	B) 8	C) 4	D) 3	E) 2
You should consider the worst case scenario: if you pick numbers 0, 1, 2, 3, 4,5 and 6 then no two numbers out of these 7 add up to 12.   Now, the next, 8th number whatever it'll be (7, 8, or 9) will guarantee that two number WILL add up to 12. So, 8 slips must be drawn to ensure that the numbers on two of the slips drawn will have a sum of 12.   Answer: 8
<result>B</result>
Each of the integers from 0 to 9, inclusive, is written on a separate slip of blank paper and the ten slips are dropped into hat. If the slips are then drawn one at a time without replacement, how many must be drawn to ensure that the numbers on two of the slips drawn will have a sum of 12?