1. Write the ratio as a fraction: \frac{2.4}{1.5} .
2. To simplify, divide both the numerator and the denominator of the fraction by the same number. Here, we can divide both by 0.3:
\[\frac{2.4 \div 0.3}{1.5 \div 0.3} = \frac{8}{5}\]
3. The simplified form of the ratio 2.4 : 1.5 is \frac{8}{5} .
Therefore, the solution is \frac{8}{5} .