What is the cost of running five 50W lamps and four 100W lamps for 10 hours if electrical energy costs 2 Kobo per KWh?

What is the cost of running five 50W lamps and four 100W lamps for 10 hours if electrical energy costs 2 Kobo per KWh?

Answer Details

P = (5 x 50) + (100 x 4)

= 650watts

Energy(kWhr) = 650 x 10-3 x 10

= 6.5 kWhr

1kWhr cost 2 kobo ; 6.5 kWhr will cost 2×6.512×6.51

= 13 kobo