The number of crosspoints needed for 10 lines in a crosspoint switch, which is…

2018

The number of crosspoints needed for 10 lines in a crosspoint switch, which is full duplex in nature and there is no self-connection, is —

  1. A.

    100

  2. B.

    45

  3. C.

    50

  4. D.

    90

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Correct answer: D

Key idea: In a full duplex crosspoint switch without self-connections, each ordered pair of distinct lines requires one crosspoint. Total ordered pairs: For n lines there are n×(n−1) ordered pairs because each of the n source lines can connect to (n−1) other destination lines.

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