11 The following data are from a study among schoolaged chil

11. The following data are from a study among school-aged children, ages 6-10 years old, living in a rural community:

Fluoridated Drinking Water________Dental Caries_____No Dental Caries

Yes    9    149

   No    14     49

Which number best describes the association between fluoridated drinking water and dental caries among school-aged children in the study above?

A. 2.11

B. 0.25

C. 3.50

D. 2.46

E. 1.02

Solution

Solution: The number of student who drinks fluoridated drinking water & have dental caries:9 And the number of student who drinks flourinated drinking water & does not have dental caries:149 Therefore total number of student Who drinks flourinated drinking water:158 Therefore ratio of student drinks flourinated water & have dental caries:9/158=0.05696. Ans: B.0.25 is the best number to describe the association between flourinated drinking water and dental caries among school-aged children , ages 6-10 years old.