Final answer:
The probability that a randomly chosen number between 1 to 20 is either a multiple of 3 or a multiple of 5 is 9 out of 20, or 9/20, which is not represented by any of the answer choices provided.
Step-by-step explanation:
When one of the numbers 1 to 20 is chosen at random, the probability that it is either a multiple of 3 or a multiple of 5 can be determined by first listing the multiples of 3 and 5 within this range. The multiples of 3 are 3, 6, 9, 12, 15, and 18, which gives us 6 outcomes. The multiples of 5 are 5, 10, 15, and 20, providing 4 outcomes. However, since 15 is a multiple of both 3 and 5, it should not be double-counted. This gives us a total of 6 + 4 - 1 = 9 favorable outcomes out of 20 possible outcomes.
The probability is therefore 9 out of 20, which simplifies to 9/20. To match this with the options provided, we must simplify 9/20. The closest option to 9/20 is option (d) 4/9, but since 9/20 does not reduce to 4/9, none of the provided options correctly represent the probability.
Therefore, the accurate probability in simplest form is 9/20, which is not listed as one of the options in the question.