Question

Цветной телевизор 2 месяца назад стоил на 20% дешевле,чем месяц назад,когда он стоил на 10% дешевле,чем сейчас.На сколько процентов дешевле стоил телевизор два месяца назад,чем сейчас?

Answer 1

Пусть сейчас цена - х, тогда месяц назад цена была на 10 % меньше, то есть 0,9х. Два месяца назад цена была на 20% меньше, чем месяц назад, то есть 0,8*0,9х=0,72х. Это значит, что два месяца назад цена была 72% от теперишней, а значит на 28% меньше.

Answer 2

Calculating the Percentage Difference in TV Price

To calculate the percentage difference in the price of the TV two months ago compared to now, we can use the given information about the price changes.

The TV was 20% cheaper two months ago compared to one month ago, and one month ago, it was 10% cheaper than it is now. We can calculate the percentage difference using the formula: \[ \text{Percentage Difference} = \frac{\text{New Value} - \text{Old Value}}{\text{Old Value}} \times 100\% \]

Using this formula, we can calculate the percentage difference.

The first step is to calculate the price of the TV two months ago compared to one month ago: \[ \text{Price two months ago} = \text{Price one month ago} - \left( \frac{20}{100} \times \text{Price one month ago} \right) \]

Then, we can calculate the price of the TV one month ago compared to now: \[ \text{Price one month ago} = \text{Price now} - \left( \frac{10}{100} \times \text{Price now} \right) \]

Finally, we can calculate the percentage difference in the price of the TV two months ago compared to now using the formula mentioned earlier.

Calculation

Using the given information, we can calculate the percentage difference in the price of the TV two months ago compared to now.

\[ \text{Price one month ago} = \text{Price now} - \left( \frac{10}{100} \times \text{Price now} \right) \] \[ \text{Price one month ago} = \text{Price now} - 0.1 \times \text{Price now} \] \[ \text{Price one month ago} = 0.9 \times \text{Price now} \]

\[ \text{Price two months ago} = 0.9 \times \text{Price now} - \left( \frac{20}{100} \times 0.9 \times \text{Price now} \right) \] \[ \text{Price two months ago} = 0.9 \times \text{Price now} - 0.18 \times \text{Price now} \] \[ \text{Price two months ago} = 0.72 \times \text{Price now} \]

Now, we can calculate the percentage difference: \[ \text{Percentage Difference} = \frac{\text{Price now} - 0.72 \times \text{Price now}}{0.72 \times \text{Price now}} \times 100\% \] \[ \text{Percentage Difference} = \frac{0.28 \times \text{Price now}}{0.72 \times \text{Price now}} \times 100\% \] \[ \text{Percentage Difference} = \frac{0.28}{0.72} \times 100\% \] \[ \text{Percentage Difference} = 38.89\% \]

Conclusion

The TV was approximately 38.89% cheaper two months ago compared to now.