An object of 1.2 cm height is placed 30 cm before a concave mirror of focal length of 20 cm toget a real image at a distance of 60 cm from the mirror. What is the height of the image formed?
Students are sitting in a row in which the position of X is 17th from the left and that of Y is 14th from the right. If they interchange their positions, X's position becomes 7th from the left. How many students are there in the row?