1. The problem asks to compare the fraction $\frac{3}{5}$ and the decimal number $1.5$ to determine if $\frac{3}{5}$ is less than or greater than $1.5$. 2. First, convert the fraction $\frac{3}{5}$ to a decimal by dividing the numerator by the denominator: $$\frac{3}{5} = 3 \div 5 = 0.6$$ 3. Now compare the two decimal values: $0.6$ and $1.5$. 4. Since $0.6$ is less than $1.5$, we conclude: $$\frac{3}{5} < 1.5$$ 5. Therefore, the correct inequality symbol to fill in the blank is $<$.