How many bricks will be required for a wall which is 8m long 6m high and 22.5cm thick if each brick measures 25cm × 11.25 cm × 6cm? 

7 Find the volume, the total surface area and the lateral surface of a cuboid which is 8m long, 6m broad and 3.5m high. 8 Find the volume of a cube whose total surface area is 486cm². 10 An open rectangular cistern when measured outside is 1.35 m long 1.08m broad and 90cm deep and is made of iron which is 2.5cm thick. Find the capacity of the cistern and the volume of the iron used. 11 A field is 80m long and 50m broad. In one corner of the field, a pit which is 10m long, 7.5 m broad and 8m deep has been dug out. The earth taken out of it is evenly spread over the remaining part of the field. Find the rise in the level of the field.