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
A hand made paper workshop can hire 8 craftsmen by paying them Rs 400 per person per day. The 9th craftsman demands Rs 450 per day. If this craftsman is hired then all other craftsmen must be paid Rs 450. The marginal resource (labour) cost of the 9th craftsman is