When testing for current in a cable with ninecolor coded wir

When testing for current in a cable with nine-color coded wires, the author used a meter to test three wires at a time. How many different tests are required for every possible pairing of three wires?

The number of tests required is ____?

Solution

Answer:-

Select 3 from 9

= 9c3
=C(9,3)
9! / (3! (9 - 3)!) = 84....answer

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