Question

A classroom is 12m long 7 metre wide and 4 metre high. find the cost of repairing the walls and ceilings at the rate of 15 rupees per square metre

Answer 1

consider the TSA of the room,
it is: $2(lb+bh+hl)$
$=2(84+28+48)$
$=2(160) =320$
this is the TSA of the room, but we shall not consider the floor, so subtract the area of the floor from the TSA of the room,
we get:
$320-(lb)=320-84=236$
cost per metre sq. is given as 15,
therefore, total cost will be $15*236=3540$
Hence, required cost for repair is rupees 3540