Final answer:
The physical therapists underestimated the rest time patients received in therapy by a certain percent.
Step-by-step explanation:
In this scenario, the physical therapists underestimated the rest time patients received in therapy by a certain percentage. To determine the percent by which the rest time was underestimated, we need more information. We are given that 75 percent of the students exercise for 60 minutes or less daily, and half of the students exercise between 20 and 60 minutes a day. However, this information does not directly provide the percent by which the rest time was underestimated.