Reema wants to buy a certain designer party dress. The shop is offering a discount of 20% on that dress which is marked at Rs 5000. If Reema was willing to pay even Rs 7000 for that dress, Reema's consumer surplus is
The angle of elevation of the top of a pillar from the foot and the top of a building 20 m high, are 60° and 30° respectively. The height of the pillar is