It would cost a man Rs. 3.50 to buy 1.0 kW h of electrical energy from the Main Electricity Board. His generator has a maximum power of 2.0 kW. The generator produces energy at this maximum power for 3 hours. Calculate how much it would cost to buy the same amount of energy from the Main Electricity Board.

The cost of electrical energy is typically given in terms of the cost per unit of energy, which is measured in kilowatt-hours (kWh). In this case, the cost is Rs. 3.50 per 1.0 kWh.
The generator produces energy at its maximum power of 2.0 kW for 3 hours. To find the total energy produced by the generator, you can use the formula:

Energy (in kWh) = Power (in kW) x Time (in hours)

So, for the generator:
Energy (in kWh) = 2.0kW × 3hours
Energy (in kWh) =6.0kWh
Now, to find the cost of this energy from the Main Electricity Board, you can use the given cost per kWh:
Cost = Energy (in kWh) × Cost per kWh
Cost = 6.0kWh×Rs.3.50/kWh
Cost = Rs.21.00
Therefore, it would cost Rs. 21.00 to buy the same amount of energy from the Main Electricity Board that the generator produces at its maximum power for 3 hours.