1.Each of the integers from 0-9, inclusive, is written on a separate slip of blank paper and the ten slips are dropped into a 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 10?
A.3 B.4 C.5 D.6 E.7
2.Set S consists of n distinct positive integers, none of which is greater than 12. What is the greatest possible value of n if no two integers in S have a common factor greater than 1?
A.4 B.5 C.6 D.7 E.11
3.This year H will save a certain amount of his income, and he will spend the rest. Next year H will have no income,but for each dollar that he saves this year, he will have 1+r dollars available to spend. In TERMS OF R, What fraction of his income should H save this year so that next year the amount he was available to spend will be equal to half the amount that he spends this year?
A.1/r+2 B.1/2r+2 C.1/3r+2 D.1/r+3 E.1/2r+3
4.Car X and Y were traveling together on a straight road at a constant speed of 55 miles per houre when car X stopped for 5 minytes. If car Y continued to travel at 55 miles per hour, how many minutes from time that car X traveling at 60 miles per hour to catch up with car Y? (Assume that the time for car X slow down and speed up was negligble.)
A.5 B.30 C.45 D.55 E.60
5.In a certain contest, F must select any 3 of 5 different gifts offered by the sponsor. From how many different combinations of 3 gifts can F make his selection?
A.10 B.15 C.20 D.30 E.60
6.If a car averaged 22.5 miles per gallon of gasoline, approximately how many kilometers per liter of gasoline did the car average?(1mile =1.6 kilometers and 1 gallon= 3.8 liters, both rounded to the nearest tenth.)
1.Each of the integers from 0-9, inclusive, is written on a separate slip of blank paper and the ten slips are dropped into a 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 10?
A.3 B.4 C.5 D.6 E.7
The worst case scenario: 0, 9, 8, 7,6, 5. Basically you pick 0 and 5, then pick one from the other 4 pairs. So choose E.
2.Set S consists of n distinct positive integers, none of which is greater than 12. What is the greatest possible value of n if no two integers in S have a common factor greater than 1?
A.4 B.5 C.6 D.7 E.11
It just ask you for the numbers of prime number smaller than 12, then plus 1.
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发表于 2011-3-1 09:54:07
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