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as a medical officer, you are required to select five persons from a group of 7 men and 6 women, to form a committee so that at least 3 men are there on the committee. in how many ways can it be done?
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+ + = 7 + + = 7 + 21 + 35 = 63 ways.
Symbol is the number of combinations of n objects taken m at a time.
See the lesson Introduction to Combinations in this site.