应用题在数学中是一种常见的问题类型，通过对实际情境进行数学建模和计算，帮助我们更好地理解和应用百分数。百分数是指以百分之一作为单位的比例数，它在日常生活和商业领域中有着广泛的应用。本文将介绍几个常见的应用题，并讲解如何使用百分数进行计算。

Application problems are a common type of mathematical problem which involves using mathematical modeling and calculations to solve real-life situations. These problems help us understand and apply percentages more effectively. A percentage is a proportion or ratio expressed in terms of hundredths, and it has various applications in everyday life and business. In this article, we will explore several common application problems and explain how to use percentages for calculations.

首先，我们来看一个购物折扣的应用题。假设某商店正在举行一次打折促销活动，原价为100元的商品打8折出售。我们需要计算出打折后的价格。首先，我们需要将“打8折”转换为百分数形式，即80%。然后，我们可以使用以下公式来计算折扣后的价格：折扣后价格 = 原价 × 折扣比例。根据这个公式，商品的折扣后价格为100 × 0.8 = 80元。

Let's start with an application problem about shopping discounts. Suppose a store is having a promotion where a product originally priced at 100 yuan is being sold at an 20% discount. We need to calculate the discounted price. First, we need to convert "20% off" into percentage form, which is 80%. Then, we can use the following formula to calculate the discounted price: Discounted Price = Original Price × Discount Rate. Applying this formula, the discounted price of the product is 100 × 0.8 = 80 yuan.

接下来，我们将考虑一个百分比增长的问题。假设某公司去年的销售额为10,000元，今年的销售额为12,000元。我们需要计算今年的销售额相对于去年增长了多少百分比。首先，我们需要计算增长的金额，即今年销售额减去去年销售额，即12,000 - 10,000 = 2,000元。然后，我们可以使用以下公式计算百分比增长率：百分比增长率 = （增长金额 / 去年销售额）× 100%。根据这个公式，本例中的百分比增长率为（2,000 / 10,000）× 100% = 20%。

Next, let's consider a problem involving percentage increase. Suppose a company had sales of 10,000 yuan last year and 12,000 yuan this year. We need to calculate the percentage increase in sales from last year to this year. First, we calculate the increase in amount, which is the current year's sales minus the previous year's sales, i.e., 12,000 - 10,000 = 2,000 yuan. Then, we can use the following formula to calculate the percentage increase: Percentage Increase = (Increase in Amount / Previous Year's Sales) × 100%. Applying this formula, the percentage increase in this example would be (2,000 / 10,000) × 100% = 20%.

最后，我们来看一个应用百分数的利润率问题。假设某公司的成本为1,000元，销售额为1,500元。我们需要计算该公司的利润率是多少百分比。利润率可以通过以下公式计算：利润率 = （销售额 - 成本）/ 销售额 × 100%。根据这个公式，本例中的利润率为（1,500 - 1,000）/ 1,500 × 100% = 33.33%。

Lastly, let's consider a problem involving profit margin using percentages. Suppose a company has costs of 1,000 yuan and sales of 1,500 yuan. We need to calculate the profit margin as a percentage for this company. The profit margin can be calculated using the following formula: Profit Margin = (Sales - Costs) / Sales × 100%. Applying this formula, the profit margin in this example would be (1,500 - 1,000) / 1,500 × 100% = 33.33%.

在以上的例子中，我们展示了如何在不同的情境中使用百分数进行计算。无论是购物折扣、增长率还是利润率，百分数都可以帮助我们更好地理解和应用数字。掌握百分数的计算方法，可以在日常生活和商业领域中应用灵活，更好地解决实际问题。

In the examples above, we have demonstrated how to use percentages for calculations in different contexts. Whether it's shopping discounts, growth rates, or profit margins, percentages can help us better understand and apply numbers. Mastering the calculation of percentages allows us to apply them flexibly in everyday life and business, enabling us to solve practical problems more effectively.

翻译对照（Translation reference）：

- 打折促销活动 (shopping discounts)

- 商品 (product)

- 原价 (original price)

- 折扣比例 (discount rate)

- 折扣后价格 (discounted price)

- 销售额 (sales)

- 百分比增长率 (percentage increase)

- 去年的销售额 (last year's sales)

- 百分数增长 (percentage increase)

- 成本 (costs)

- 利润率 (profit margin)