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In a survey of 100 students, the numbers taking various courses were found to be
English, 59; mathematics, 44; chemistry, 48; English and mathematics, 24; English and chemistry, 26; mathematics and chemistry, 31;
and courses in all three areas, 16.
(a) How many students were taking mathematics, but neither English nor chemistry?
M - EM - MC + EMC = 44 - 24 - 31 + 16 = 5.
(b) How many were taking mathematics and chemistry, but not English?
MC - EMC = 31 - 16 = 15.
(c) How many were taking English and chemistry, but not mathematics?
EC - EMC = 26 - 16 = 10.
Solved.
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In this solution, two-letter abbreviation means intersection of two sub-sets.