The apartment has two 60W and two 40W light bulbs. Each of them is turned on for 3 hours a day

The apartment has two 60W and two 40W light bulbs. Each of them is turned on for 3 hours a day. Determine the cost of the energy consumed by the lamps in one month (30 days). Current tariff: 2.2 kW * h.

1) Electricity per day:

P1 = (2 * P1 + 2P2) * t1, where P1 is the power of the first lamp (P1 = 60 W), P2 is the power of the second lamp (P2 = 40 W), t1 is the operating time (t1 = 3 hours).

P1 = (P1 + 2P2) * t1 = (2 * 60 + 2 * 40) * 3 = 600 W * h.

2) Electricity per month:

P30 = P1 * t2, where t2 is the operating time (t2 = 30 days).

P30 = P1 * t2 = 600 * 30 = 18000 W * h = 18 kW * h.

3) Cost:

S = P30 * T, where T is the tariff (T = 2.2 rubles kW * h).

S = P30 * T = 18 * 2.2 = 39.6 rubles.