Study the following pie-chart and answer the question given below.

Breakup (degree wise) of the number of students studying in classes VI to X in a school

Number of students in Class VIII = 155

In Class IX, the ratio of boys and girls is 2 : 3 and 55$$\frac 59$$​ % of the students in Class X are girls.

The numberof girls in Class X is what percent more than the number of boys in Class IX?

Correct option is D

​Given :

​From the pie-chart (degree wise):

Class VI = 84.6°

Class VII = 75.6°

Class VIII = 63°

Class IX = 72°

Class X = 64.8°

Number of students in Class VIII = 155

In Class IX, boys : girls = 2 : 3

In Class X, 55$$\dfrac{5}{9}\% = \dfrac{5}{9}$$​ are girls

Formula Used :

​$$\text{Students} = \frac{\text{Degree}}{360^\circ} \times \text{Total students}$$​​

​$$\text{Percentage more} = \frac{\text{Difference}}{\text{Base value}} \times 100$$​​

Solution :

Find total number of students

​$$63^\circ \rightarrow 155 \text{ students}$$​​

​$$360^\circ \rightarrow \frac{155 \times 360}{63}$$​​
= 88$$5.7 \approx 886 \text{ students}$$​​

Class IX students
​$$= \frac{72}{360} \times 886 \approx 177$$​​

Class X students
​$$= \frac{64.8}{360} \times 886 \approx 160$$​​

Boys : Girls = 2 : 3
Total parts = 5

​$$\text{Boys in IX} = \frac{2}{5} \times 177 \approx 71$$​​

​$$\text{Girls in X} = \frac{5}{9} \times 160 \approx 89$$​​

Difference:
= 89 - 71 = 18

​$$\text{Required \%} = \frac{18}{71} \times 100 \approx 25$$​%