Given: Number of total boys and girls =540 The ratio of boys and girls is 5:4 The total number of girls increase =20% Explanation: Let the proportional ratio = x According to the question, 5x+4x=540 ⇒9x=540 ⇒x=60 So Boys = 5x = 5 × 60 = 300 Girls =4x=4×60=240 Now, Girls increase =240×20%=48 Number of total girl =240+48=288 The new ratio of boys and girls =300:288=25:24 ∴ The new ratio of boys and girls is 25:24. Shortcut: Given: Number of total boys and girls = 540 The ratio of boys and girls is 5 : 4 The total number of girls increase = 20% Explanation: Number of boys =540×(5/9)=300 Number of girls = 540 - 300 = 240 Number of girls after increase of 20%=240×120%=288 The new ratio of boys and girls =300:288=25:24 ∴ The new ratio of boys and girls is 25 : 24.