SOLUTION: In a survey of 225 students, 100 were taking mathematics and 70 were taking psychology. What is the least number of students that could be taking both courses

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Question 1118208: In a survey of 225 students, 100 were taking mathematics and 70 were taking psychology. What is the least number of students that could be taking both courses
Found 2 solutions by ikleyn, Shin123:
Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
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In a survey of 225 students, 100 were taking mathematics and 70 were taking psychology.
What is the least number of students that could be taking both courses
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Answer. 0 (zero, ZERO).

Solution 

We are given the set consisting of 225 elememts.


And two its subsets: one of 100 elements and the other of 70 elements.


We don't know if these subsets have empty or non-empty intersection.


The problem asks to estimate the minimal number of elements in the intersection.


The answer is 0 (zero, ZERO), since the two subsets may have the empty intersection: 
there is no obstacles or restrictions; nothing prohibits it.


Answer by Shin123(626) About Me  (Show Source):
You can put this solution on YOUR website!
The least amount is 0. Both subsets may not intersect or they could. Therefore,the minimum is 0.