Task 11. (16 points)

One way to save on utility bills is to use the night tariff (from 23:00 to 07:00). To apply this tariff, a multi-tariff meter needs to be installed.

The Romanov family is considering purchasing a multi-tariff meter to reduce their utility bills. The cost of the meter is 3500 rubles. The installation cost of the meter is 1100 rubles. On average, electricity consumption is 300 kWh per month, with 230 kWh used from 23:00 to 07:00.

The cost of electricity when using a multi-tariff meter: from 07:00 to 23:00 - 5.2 rubles per kWh, from 23:00 to 07:00 - 3.4 rubles per kWh.

The cost of electricity when using a standard meter is 4.6 rubles per kWh.

Determine how much the Romanov family will save by using a multi-tariff meter over three years.

In your answer, provide only the number without units of measurement!
# Solution:

2) use of a multi-tariff meter:

$$
3500+1100+(230 * 3.4+(300-230) * 5.2) * 12 * 3=45856 \text { rub. }
$$

3) use of a typical meter

$$
300 * 4.6 * 12 * 3=49680 \text { rub. } \quad \text {. } \quad \text {. }
$$

the savings will be

$49680-45856=3824$ rub.

## Answer: 3824