A geneticist conducts a study to investigate the prevalence of a certain genetic marker in a particular population of United States (US ) adults. During the study.the geneticist observes the genetic code of 1,000 randomly selected US adults in that population and finds that 350 of those adults have the genetic marker.According to the results of the study.what is the ratio of observed adults with the genetic marker to observed adults without the genetic marker?

## Step 1<br />The geneticist observed 1,000 adults in total. Among them, 350 adults had the genetic marker. Therefore, the number of adults without the genetic marker is the total number of adults minus the number of adults with the genetic marker.<br />### **Number of adults without the genetic marker = Total number of adults - Number of adults with the genetic marker**<br />## Step 2<br />Substitute the given values into the formula.<br />### **Number of adults without the genetic marker = 1,000 - 350 = 650**<br />## Step 3<br />The ratio of observed adults with the genetic marker to observed adults without the genetic marker is the number of adults with the genetic marker divided by the number of adults without the genetic marker.<br />### **Ratio = Number of adults with the genetic marker / Number of adults without the genetic marker**<br />## Step 4<br />Substitute the calculated values into the formula.<br />### **Ratio = 350 / 650 = 7/13**