Answer:
3/8
Step-by-step explanation:
A ratio is expressed in lowest terms by removing common factors from numerator and denominator.
[tex]\dfrac{2.7\text{ hr}}{7.2\text{ hr}}=\dfrac{3\cdot0.9\text{ hr}}{8\cdot0.9\text{ hr}}=\boxed{\dfrac{3}{8}}[/tex]