In a house 5 bulbs of 25 watts each are used for 6 hours a day. calculate the unit of electricity consumed in a month of 30 days. also find the total cost if one unit electricity cost 1.50 rs.

(5 bulbs) x (25 watt/bulb) x (6 hour/day) x (30 day/month) =

             (5 x 25 x 6 x 30) watt-hour/month =

                 22,500 watt-hour/month .

The most common unit of electrical energy used for billing purposes
is the 'kilowatt-hour' = 1,000 watt-hours .

               22,500 watt-hour/month =  22.5 kWh/month.

             (22.5 kWh/month) x (1.50 Rs/kWh) =  33.75 Rs / month