The cross-section of a tunnel perpendicular to its length is a trapezium ABCD as shown in the following figure; also given that : AM = BN; AB = 7 m; CD = 5 m. The height of the tunnel is 2.4 m. The tunnel is 40 m long. Calculate :

(i) the cost of painting the internal surface of the tunnel (excluding the floor) at the rate of ₹ 5 per m² (sq. metre).

(ii) the cost of paving the floor at the rate of ₹ 18 per m².

Water is discharged from a pipe of cross-section area 3.2 cm² at the speed of 5m/s. Calculate the volume of water discharged :

(i) in cm³ per sec.

(ii) in litres per minute.

The cross-section of a piece of metal 4 m in length is shown below. Calculate :

(i) the area of the cross-section;

(ii) the volume of the piece of metal in cubic centimetres.

If 1 cubic centimetre of the metal weighs 6.6 g, calculate the weight of the piece of metal to the nearest kg.

A rectangular water-tank measuring 80 cm x 60 cm x 60 cm is filled from a pipe of cross-sectional area 1.5 cm², the water emerging at 3.2 m/s. How long does it take to fill the tank?