If 20 boys from each hostel left their hostel then find the average of remaining number of boys in all the hostels?

Let number of girls in hostel B=100x Then number of boys in hostel B=200x Number of girls in hostel A= 130x Number of boys in hostel C=120+100=220 Number of girls in hostel C=1000-220=780 Total number of girls in hostel A and that of in hostel D=446 Number of girls in hostel D=(446-130x) Number of boys in hostel D=302 ATQ 200x – 302 = 98 ⇒ x = 2 /

Required average = $frac{{100 + 380 + 200 + 282}}{4} = 240.5$