Epidemiologists decided to investigate the effect of sunscreens on sunburns. They ran an epidemiologic study to see the association of sunscreens and sunburns. Overall, 460 people have enrolled in the study. Investigators randomly allocated 230 people to the treatment group (sunscreens) and 230 to the control group (placebo). They exposed those 460 people to the high mountain trail on a sunny day. At the end of the study, 30 people developed sunburns in the sunscreen group and 130 people developed sunburns in the placebo group. What is the relative risk of sunburns in the sunscreen treatment group compared with the control group in this study

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

  or  

step-by-step explanation:

if the four friends split the cost, p, of the pizza evenly, then each friend pays one-fourth of the cost of the pizza.

the expression is   or