# If out of 20 consecutive whole numbers two are chosen at random, then find the probability that their sum is odd.

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If out of 20 consecutive whole numbers two are chosen at random, then find the probability that their sum is odd.

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Correct Answer - (10)/(19)
The total number of ways in which 2 integers can be chosen from the given 20 integers is .^(20)C_(2).
The sum of the selected numbers is odd if exactly one of them is even and only one is odd. Therefore, the favorable number of outcomes is (.^(10)C_(1)xx.^(10)C_(1))/(.^(20)C_(2)) = (10)/(19)