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The probability that a number selected at random from the first 50 natural numbers is a composite number is__________?

Correct answer: B. 17/25

  • A. 21/25
  • B. 17/25
  • C. 4/25
  • D. 8/25

Explanation

From 1 to 50 there are 15 primes, and 1 is neither prime nor composite. Therefore, the number of composite numbers is 50 - 15 - 1 = 34, so the probability is 34/50 = 17/25. The likely mistake is choosing 21/25 by subtracting only the 15 primes and wrongly treating 1 as composite.

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