In a class, the average marks of girls in an examination is 75 and that of the boys is 64. The average score of the whole class is 68.4. What is the percentage of the girls in the class?
- A50%
- B66.60%
- C40%
- D45%
Solution & Step-by-step Explanation
Using the method of Alligation:
Average of Girls=75Average of Boys=64
Mean Average=68.4
Ratio of Girls to Boys=(68.4−64):(75−68.4)
Ratio=4.4:6.6=2:3
Therefore, the percentage of girls in the class is:
Percentage of girls=
2+3
2
×100%=
5
2
×100%=40%
Average of Girls=75Average of Boys=64
Mean Average=68.4
Ratio of Girls to Boys=(68.4−64):(75−68.4)
Ratio=4.4:6.6=2:3
Therefore, the percentage of girls in the class is:
Percentage of girls=
2+3
2
×100%=
5
2
×100%=40%