6. Gru and the Minions plan to earn money by mining cryptocurrencies. For mining, they chose Ethereum (Ethereum) as one of the most stable and promising currencies. For this, they bought a system unit for 9499 rubles and two video cards for 31431 rubles each. The power consumption of the system unit is 120 W, and each video card - 125 W. The mining speed on one video card is 32 million hashes per second, allowing them to earn 0.00877 Ethereum per day on one video card. 1 Ethereum equals 27790.37 rubles. How many days will it take for the villains' investment to pay off, taking into account the cost of electricity at 5.38 rubles per $1 \mathrm{kWt} / \mathrm{h}$? (20 points)

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# Answer:

With two video cards, you can earn $2 \times 0.00877 \times 27790.37 = 487.44$ rubles per day. The power consumption of one system unit and two video cards is $120 + 125 \times 2 = 370$ watts per hour, or 8.88 kWh per day, which amounts to 47.77 rubles spent on electricity per day. Capital expenses amount to 72361 rubles, and the income for 1 day is $487.44 - 47.77 = 439.67$ rubles. Thus, the system will start generating profit after 164.58 days, assuming the mining difficulty remains unchanged.

## Criteria

20 points - for correctly conducted calculations (a difference of no more than 1 day from the reference solution is allowed due to rounding errors during calculations);

15 points - correct logical reasoning, but arithmetic errors are present;

10 points for correctly calculated electricity costs or correctly calculated mining income;

5 points - for providing the correct calculation of electricity consumption or income.

Maximum score for the task is 100 points.

## Financial Literacy Olympiad On-site Stage $8-9$ Grades Variant 2 Answers and Solutions