There are 30 students in a class. 12 of them play basketball, 15 of them play fo

游客2024-01-12  8

问题 There are 30 students in a class. 12 of them play basketball, 15 of them play football, and 19 of them play pingpang. If 7 of them play all three activities and exactly 6 of them play two activities, how many of them play none of the three activities?

选项 A、2
B、0
C、8
D、4
E、6

答案 D

解析 设玩三种运动的人分别为A,B,C,A=12,B=15,C=19,7个人三种运动都玩,那么P=7,6个人玩两种运动,那么m=6,代入公式:30=12+15+19-6-2×7+N,得到N=4,选择D。
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