Tests will be run on five different coatings used to protect fiber optics cables from extreme cold.

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Question:

Tests will be run on five different coatings used to protect fiber optics cables from extreme cold. These tests will be conducted in random order.
(a) In how many orders can the tests be run?
(b) If two of the coatings are made by the same manufacturer, what is the probability that tests on these coatings will be run back to back?