Question

If the excavation of earth is done manually then it costs Rs. 80 per m³. A Machine can excavate at a fixed cost of Rs. 60000 plus a variable cost of Rs. 20 per m³. The quantity of earth for which the cost of excavation by machine will be equal to the cost by manual excavation is
1. 500 m³
2. 1000 m³
3. 1500 m³
4. 2000 m³

Answer 1

Correct Answer - Option 2 : 1000 m³

Calculation:

Let us assume x m³ quantity of earth are excavated

if excavations are done by manually then total cost of excavation = 80x...........(i)

If excavations are done by machine then total cost of excavation = 60000 + 20x..........(ii)

Then quantity of earth for which the cost of excavation by machine will be equal to the cost by manual excavation. so equate equation (i) and (ii)

80x = 60000 + 20x

60x = 60000

x = 1000 m³