Multiple choice

A box contains $20$ balls bearing numbers, $1,2,3,4, .....20$. A ball is drawn at random from the box. What is the probability that the number on the ball is prime number

  1. $\dfrac{1}{5}$
  2. $\dfrac{2}{5}$
  3. $\dfrac{3}{5}$
  4. $\dfrac{4}{5}$
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B Correct answer
Explanation

The prime numbers between 1 and 20 are 2, 3, 5, 7, 11, 13, 17, 19. There are 8 such numbers. The probability is 8/20 = 2/5.

AI explanation

The box contains 20 balls numbered from 1 to 20, making the total number of possible outcomes 20. The prime numbers in this range are 2, 3, 5, 7, 11, 13, 17, and 19, yielding a total of 8 favorable outcomes. Using the classical probability formula, the probability of drawing a prime number is 8/20, which simplifies to 2/5.

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