A parallelogram and a rectangle stand on the same base and on the same side of the base with the same height. If $I_ 1$ , $I_ 2$ be the perimeters of the parallelogram and the rectangle respectively, then which one of the following is correct?
A cylindrical tube open at both ends is made of metal. The internal diameter of the tube is 6 cm and length of the tube is 10 cm. If the thickness of the metal used is 1 cm, then the outer curved surface area of the tube is
For a plot of land of 100 m $\times$ 80 m, the length to be raised by spreading the earth from stack of a rectangular base 10 m $\times$ 8 m and vertical section being a trapezium of height 2 m. The top of the stack is 8 m $\times$ 5 m. How many centimeters can the level raised?