Answer :

To determine which number produces an irrational number when multiplied by 0.5, let's evaluate each option step-by-step.

Option A: [tex]\(\sqrt{16}\)[/tex]

1. Compute [tex]\(\sqrt{16}\)[/tex]:
[tex]\[ \sqrt{16} = 4 \][/tex]

2. Multiply by 0.5:
[tex]\[ 0.5 \times 4 = 2 \][/tex]

The result is 2, which is a rational number.

Option B: [tex]\(0.555 \ldots\)[/tex]

1. Given [tex]\(0.555 \ldots\)[/tex], which is actually 0.555 repeated (or simply, a rational number).

2. Multiply by 0.5:
[tex]\[ 0.5 \times 0.555 \ldots = 0.2775 \][/tex]

The result is 0.2775, which is a rational number.

Option C: [tex]\(\frac{1}{3}\)[/tex]

1. Compute [tex]\(\frac{1}{3}\)[/tex]:
[tex]\[ \frac{1}{3} \approx 0.333 \ldots \][/tex]

2. Multiply by 0.5:
[tex]\[ 0.5 \times \frac{1}{3} = \frac{1}{6} \approx 0.1667 \][/tex]

The result is [tex]\(\frac{1}{6}\)[/tex], which is also a rational number.

Option D: [tex]\(\sqrt{3}\)[/tex]

1. Compute [tex]\(\sqrt{3}\)[/tex]:
[tex]\[ \sqrt{3} \approx 1.732 \][/tex]

2. Multiply by 0.5:
[tex]\[ 0.5 \times \sqrt{3} \approx 0.5 \times 1.732 \approx 0.866 \][/tex]

The result is [tex]\(0.5 \times \sqrt{3}\)[/tex], which is still an irrational number because the product of a rational number (0.5) and an irrational number ([tex]\(\sqrt{3}\)[/tex]) is irrational.

Thus, the option that when multiplied by 0.5 produces an irrational number is:

[tex]\[ \boxed{4} \][/tex]