Total number of students in different subjects of a college and percentage of girls and boys are shown in the below table. Girl students and boy students are NOT having multiple subjects.
Subjects Number of Students Girls % Boys %
Mathematics 840 40 60
Chemistry 220 70 30
Physics 450 30 70
Biology 200 80 20
What is the ratio of girl students of Mathematics and Chemistry to the number of boy students of Physics and Biology?

Step 1: Find the number of girl students in Mathematics and Chemistry:
Girl students in Mathematics = 40% of 840=
100
40
​
×840=336

Girl students in Chemistry = 70% of 220=
100
70
​
×220=154

Total Girls=336+154=490
Step 2: Find the number of boy students in Physics and Biology:

Boy students in Physics = 70% of 450=
100
70
​
×450=315

Boy students in Biology = 20% of 200=
100
20
​
×200=40

Total Boys=315+40=355
Step 3: Find the ratio of girl students to boy students:

Ratio=
355
490
​

Dividing both terms by 5:

Ratio=
71
98
​