Average of the height of 252 students of a school is 48. If the average of the height of the boys is 51 and the average of the height of th…

Total height of 252 students = Average × Number of students = 252 × 48

Let the number of boys be x and the number of girls be (252 - x)

Total height of boys = Average height of boys × Number of boys = 51 × x

Total height of girls = Average height of girls × Number of girls = 30 × (252 - x)

Now,

252 × 48 = 51 × x + 30 × (252 - x)

⇒ 252 × 48 - 252 × 30 = 51x - 30x

⇒ Number of boys = x = 216

Total height of boys = 216 × 51 = 11016

Number of girls = 36

Total height of girls = 36 × 30 = 1080

∴ Required ratio = 51 : 5