Electrical energy consumed by 1000 W appliance used for one hour is one unit.
`2000 W` applianceused for two hours consumes 4 units of electrical energy.
In thirty days, the consumption is 120 units. Ten 100 W bulbs used for one hour consume for 1 unit of energy.
if they are used for 4 hours, energy consumed `= 4` units.
In thirt days, they consume `120` units.