doctors are interested in seeing if lifting weights to alleviate back pain is effective. twenty five volunteers are asked to rank their level of pain on a scale from one to ten. for the next two months, they then exercise for 2 months with a physical therapist. the volunteers focus on different weight lifting exercises that strengthen the back. twenty five volunteers are again asked to rank their level of pain on a scale from one to ten. was the amount of pain less after completing the exercises?