Answer Happy

SCENARIO: 1236 Marine recruits entered training during one week
in June. Marine recruits are medically examined and must be injury
and illness free before beginning training. 112 refused to
participate in a study to follow them during 12 weeks of training
for the development of stress fractures. All recruits who consented
to participate (everyone but those who refused to participate) were
successfully followed for all 12 weeks. During the 12 weeks, 55
recruits developed a stress fracture. Of these 55, 26 subjects
suffered stress fractures in the first 6 weeks and each of these 26
were fully recovered within 5 weeks. The shortest recovery time
among those suffering stress fractures after week 6 was 7.5 weeks.
At the beginning of training it was determined that 20% of
participants were classified as being in “poor physical fitness.”
The remaining recruits were in “better than poor physical fitness.”
The incidence of stress fractures in the poor physical fitness
group was 9.8%.
What PERCENT of stress fractures in the poor fit group
could be reduced by increasing fitness to better than
poor?
Among all recruits, what percent of stress fractures
could be reduced by increasing fitness to better than
poor?
What is the relative risk for stress fracture if a
recruit is in poor fitness?