How much does it cost to use a 2.5kW electric fire for 4 hours if electricity costs $7.50 per unit?

$75

Explanation:

The unit of electricity is kilowatt-hour. Considering that 2.5 kW run for 4 hours, the consumption sums up to be 2.5*4=10 kWh. This is the units charged. Since it is given that 1kWh costs $7.5 then to get the the cost of 10kwh is given by cross multiplication ie

1kwh=7.5

10kwh=?

10kwh*$7.5/1kwh=$75

The total cost incurred for using the appliance for 4 hours is equivalent to $75

 $75

Explanation:

Given parameters:

Power = 2.5kW

Time  = 4hrs

Cost  = $7.50 per unit

Unknown:

Cost = ?

Solution:

This problem deals with household or industrial power consumption. It is a straight forward problem.

We have been given the rate;

           1kWh of electricity  = $7.50

Energy consumption  = Power x time

                                     = 2.5kW x 4hrs

                                      = 10kWh

        if;

                1kWh  is billed at $7.5

                 10kWh will yield  $75