A circle is inscribed in a given square and another circle is circumscribed about the square. What is the ratio of the area of the inscribed circle to that of the circumscribed circle ?

How many bricks each measuring 50 cm x 20 cm x 12 cm will be needed to construct a wall be needed to construct a wall 16m long, 12m high and 45 cm thick ? 

 A well with 28 m inside diameter is dug 16 m deep. The earth taken out of it has been evenly spred all around it to a width of 21 m to from an embankment. Find the height of the embankment