Frankin B.R.

Petya and Vasya are trading on the stock market. Some days are lucky, and on such days Petya's capital increases by 1000, and Vasya's capital increases by $10 \%$. And on the other days, which are unlucky, Petya's capital decreases by 2000, and Vasya's capital decreases by $20 \%$. After some time, Petya's capital returned to its initial level. What happened to Vasya's capital: did it decrease, increase, or remain the same?
For one bad day, Petya's capital decreases by as much as it increases over two good days. Since in the end Petya's capital was the same as at the beginning, the number of good days was twice the number of bad days.

On a good day, Vasya's capital is multiplied by 1.1, and on a bad day by 0.8. Since the product does not change with the rearrangement of factors, the result for Vasya is the same as if two good days were followed by one bad day. In this case, over the first three days, Vasya's capital will be multiplied by $1.1 \cdot 1.1 \cdot 0.8$ $=0.968<1$, meaning it will decrease. Over the next three days, it will decrease again, and so on. Therefore, in the end, Vasya's capital will decrease.

## Oтвет

Decreased.