To convert a percentage to a decimal, you divide the percentage by 100. Let's follow the steps to convert 304.9% to a decimal:
1. Take the percentage value, which is 304.9.
2. Divide this value by 100 to convert it to a decimal.
[tex]\[
304.9 \div 100 = 3.049
\][/tex]
Thus, 304.9% written as a decimal is 3.049.
So, the correct answer is:
D. 3.049
