The length of a ladder is exactly equal to the height of the wall it is resting against. Iflower end of the ladder is kept on a stool of height 3 m and the stool is kept 9 m awayfrom the wall, the upper end of the ladder coincides with the top of the wall. Then,the height of the wall is:
A rectangular tank measuring 5m x 4.5 m x 2.1 m is dug in the centre of the field measuring 13.5.m x 2.5. The earth dug out is spread evenly over the remaining portion of afield. How much is the level of the field raised ?