you are interested in studying the possible relationship between drinking mountain dew and a teenager's willingness to bungee jump from a terrifying height of 764 ft. your study involves a total of 500 teenagers, with 250 in each of two groups. you assemble the groups on the basis of their past history of mountain dew consumption, and you prospectively determine the incidence of bungee jumping. you exclude subjects with a prior history of bungee jumping. over a 5-year period, 135 of the exposed group and 38 of the unexposed group engage in jumping. calculate the relative risk of bungee jumping among the exposed.