SOLUTION: 1. Yolanda has seven CDs that she is going to give away. She lets her best friend choose two of the seven CDs. How many different groups of two CDs are possible?
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Question 1168477: 1. Yolanda has seven CDs that she is going to give away. She lets her best friend choose two of the seven CDs. How many different groups of two CDs are possible? Answer by ikleyn(52780) (Show Source):
In this problem, by DEFAULT, the order of the CDs in groups does not matter:
the group of two CDs (A,B) is the same as the group (B,A).
There are = 7*3 = 21 such groups.
Such objects are called COMBINATIONS in Mathematics.
