Out of a total 85 children playing badminton or table tennis or both, total number of girls in the group is 70% of the total number of boys in the group. The number of boys playing only badminton is 50% of the number of boys and the total number of boys playing badminton is 60% of the total number of boys. The number of children playing only table tennis is 40% of the total number of children and a total of 12 children play badminton and table tennis both. What is the number of girls playing only badminton?
Correct Answer: Option B
Let us consider the number of boys to be x.
Number of girls = 70% of x
Therefore, x + 70% of x = 85
\(\begin{array}{l} \Rightarrow {\rm{}}x + \frac{{70 \times x}}{{100}} = 85\\ \Rightarrow {\rm{}}x + \frac{{7x}}{{10}} = 85 \end{array}\)
⇒ 10x + 7x = 850
⇒ 17x = 850
⇒ x = 850/17
⇒ x = 50
Therefore, number of boys = 50 and the number of girls are (85 – 50) = 35
Number of boys playing only badminton = 50% of boys \(= \frac{{50}}{{100}} \times 50{\rm{}} = {\rm{}}25{\rm{}}\)
∴ Total number of boys playing Table Tennis = 50 – 25 = 25
Total number of boys playing badminton = 60% of boys = \(\frac{{60}}{{100}} \times 50 = {\rm{}}30\)
∴ Total number of boys playing both table tennis and badminton = 30 – 25 = 5
∴ Total number of boys playing only Table Tennis = 25 – 5 = 20
Number of children playing only table tennis = 40% of all children \(= {\rm{}}\frac{{40}}{{100}} \times 85 = {\rm{}}34\)
∴ Number of girls playing only Table tennis = 34 – 20 = 14
Total number of children playing badminton and tennis both = 12
∴ total number of girls playing both badminton and table tennis both = 12 – 5 = 7
Therefore, number of girls playing only badminton = 35 – (14 + 7) = 14
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