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10年1月sat 1.At north high school,the ski club has 15 members

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10年1月sat
1.At north high school,the ski club has 15 members and the debate club has 12 members.If a total of 11 students belong to only one of the two clubs,how many students belong to both clubs?
A.2 B.7 C.8 D.12 E.16
2.The digits 1,2,3,and 4 are to be arranged randomly to make a positive four-digit integer.What is the probability that the digits 1,2,and 3 will be directly next to each other,in that order,from left to right?
A 1/12 B 1/8 C 1/6 D 1/4 E 1/3
1,
suppose only x students belong to ski club, only y students belong to debate club, z students belong to both clubs.
11=x+y,
15=x+z,
12=y+z,
27=x+y+2z=11+2z,
16=2z,
z=8.
Answer is C.8.

2,
4/4!=1/3!=1/6
Answer is C.1/6