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This semester, each of the 90 students in a certain class
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11 Nov 2006, 05:49
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This semester, each of the 90 students in a certain class took at least one course from A, B, and C. If 60 students took A, 40 students took B, 20 students took C, and 5 students took all the three, how many students took exactly two courses? A. 15 B. 20 C. 25 D. 30 E. 35
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Re: This semester, each of the 90 students in a certain class
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11 Nov 2006, 06:46
Only A = 60  5  AB  AC = 55  AB  AC
Only B = 40  5  AB  BC = 35  AB  BC
Only C = 20  5  AC  BC = 15  AC  BC
(55 AB  AC) + (35ABBC) + (15ACBC) + 5 + AB + AC + BC = 90
110  AB  AC  BC = 90
AB+ AC+BC =20




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Re: This semester, each of the 90 students in a certain class
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11 Nov 2006, 06:30
90=60+40+20(two class)+5
two class =35
only two class =353*5=20



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Re: This semester, each of the 90 students in a certain class
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04 Dec 2012, 22:47
Could someone explain this part?
only two class =353*5=20



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Re: This semester, each of the 90 students in a certain class
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05 Dec 2012, 02:12
anon1 wrote: Could someone explain this part?
only two class =353*5=20 Check here: ADVANCED OVERLAPPING SETS PROBLEMS
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Re: This semester, each of the 90 students in a certain class
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18 Aug 2013, 04:40
Total=60+40+20X2*All three.
90=60+40+20X10
X=20



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Re: This semester, each of the 90 students in a certain class
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18 Aug 2013, 12:40
johnycute wrote: This semester, each of the 90 students in a certain class took at least one course from A, B, and C. If 60 students took A, 40 students took B, 20 students took C, and 5 students took all the three, how many students took exactly two courses? Exactly two courses : A+B+C  2(A n B n C)  (A u B u C ) = 60 + 40 + 20  2 * 5  90 = 20 (Answer)



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Re: This semester, each of the 90 students in a certain class
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04 Apr 2018, 16:48
johnycute wrote: This semester, each of the 90 students in a certain class took at least one course from A, B, and C. If 60 students took A, 40 students took B, 20 students took C, and 5 students took all the three, how many students took exactly two courses? We can use the formula: Total = A + B + C  double  2(triple) + neither Letting d = the number of students taking exactly two courses, we have: 90 = 60 + 40 + 20  d  2(5) + 0 90 = 110  d d = 20
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Re: This semester, each of the 90 students in a certain class
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05 Sep 2019, 12:49
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Re: This semester, each of the 90 students in a certain class
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