Study the following table and answer the question below.

Find the ratio of the number of female students who opted biology in school B and school D.

7 : 9

In school B , Number of students enrolled in biology = 36% of 400 = 144

Number of female students = \(\frac{7}{12}\) × 144 =  84

In school D , Number of students enrolled in biology = 18% of 800 = 144

Number of female students = \(\frac{9}{12}\) × 144 =  108

Required ratio  ,    84 : 108  = 7 : 9