Calculate the running costs of a filament lamp with a 60 W bulb and a CFL lamp with a 15 W bulb for 15 hours. 1 kWh costs 10p.
cost = power (kW) × time (hours) × price (per kWh)

the cost of running the bulbs is 11.25p

Explanation:

Given;

cost of running 1 kwh = 10 p

power of filament bulb, P = 60 W

power of the CFL bulb, P = 15 W

time of power consumption, t = 15 hours

Total Energy consumed;

E = (60W + 15W) x 15 hours

E = (75)(15)

E = 1125 Wh

E = 1.125 kWh

Cost of 1.125 kWh  =   1.125 x 10p

                               = 11.25p

Therefore, the cost of running the bulbs is 11.25p