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Two distinct natural numbers from 1 to 9 are picked at random. What is the probability that their product has 1 in its unit place?

Options

  1. A1 81
  2. B1 72
  3. C1 18
  4. D1 36

Correct answer

D. 1 36

Step-by-step solution

There are only two combination are possible (3,7) , (7,3) such that their product has 1 in its unit place. So, required probability = 2 9 8 = 1 36

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