Multiple choice

A number is selected at random from first 40 natural numbers. What is the chance that it is a multiple of either 4 or 14?

  1. 1/5

  2. 11/40

  3. 3/10

  4. 10/40

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Multiples of 4 up to 40: 4, 8, 12, 16, 20, 24, 28, 32, 36, 40 (10 numbers). Multiples of 14 up to 40: 14, 28 (2 numbers). The number 28 is common. Using inclusion-exclusion: 10 + 2 - 1 = 11. Probability = 11/40.

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