Answer:
0.23
Step-by-step explanation:
Total number enrolled in the study = 460
Number of subjects in treatment group = 230
Number who developed sunburn in treatment group = 30
Number of subjects in placebo = 230
Number who developed sunburn in placebo = 130
Proportion of treatment group who developed sunburn = 30 / 230 = 0.130
Proportion of placebo who developed sunburn = 130 / 230 = 0.565
The relative risk of sunburn in treatment group compared with control group :
Proportion of sunburn in treatment / proportion of sunburn in placebo
0.130 / 0.565 = 0.23