[tex]Dane:\\P = 2 \ 500 \ W = 2,5 \ kW\\t_1 = 15 \ min = \frac{15}{60} \ h = 0,25 \ h\\n = 30 \ dni\\t = n\cdot t_1 = 30\cdot0,25 \ h = 7,5 \ h\\k = 65 \ \frac{gr}{kWh} = 0,65 \ \frac{zl}{kWh}\\Szukane:\\K = ?\\\\Rozwiazanie\\\\W = P\cdot t\\\\W = 2,5 \ kW\cdot 7,5 \ h = 18,75 \ kWh\\\\K = k\cdot W\\\\K = 0,65\frac{zl}{kWh} \cdot18,75 \ kWh\\\\\boxed{K = 12,19 \ zl}[/tex]
Odp. Koszt zużytej energii elektrycznej wynosi 12,19 zł.
