Grade 5

Grade 5Data and Probability


Range of Data


In mathematics, especially when studying data and probability, it is important to understand the concept of the range of data. The "range" is a simple measure of how spread out the numbers in a data set are. This measure helps us understand the variability of the data. In other words, it shows how much the data varies from the lowest number to the highest number.

What is the range?

Range is the difference between the highest and lowest values in a data set. It gives us a sense of the spread or dispersion of the values.

To calculate the range, you use the following formula:

Range = Maximum Value - Minimum Value

Why is range important?

The range is important because it tells us how spread out the data points are. If the range is large, it means the data has more variability or dispersion. If the range is small, the data points are closer together.

For example, if your test scores are between 40% and 90%, the range is 50. This shows a significant difference between the lowest and highest scores. In contrast, if scores are between 70% and 80%, the range is 10, which shows that the scores are very close to each other.

How to find the range

Finding the limit of a set of numbers is simple. Let's break it down into steps:

  1. Find the smallest number in the data set.
  2. Find the largest number in the data set.
  3. Subtract the smallest number from the largest number.

Let's look at some examples to see this in action:

Example 1: Small data set

Consider the following data set:

3, 8, 12, 5, 9

Step 1: Identify the smallest number (which is 3).

Step 2: Identify the largest number (which is 12).

Step 3: Subtract the smallest from the largest:

Range = 12 - 3 = 9

Thus, the range of this data set is 9.

Example 2: Test scores

Imagine you collected the test scores of five students:

67, 75, 82, 91, 88

Step 1: Identify the smallest score (which is 67).

Step 2: Identify the highest score (which is 91).

Step 3: Subtract the smallest score from the largest score:

Range = 91 - 67 = 24

The range of these test scores is 24.

Visual example

We can also represent the range visually using a simple number line:

3 5 8 9 12

In this number line you can see the data points 3, 5, 8, 9, and 12. The range is 12 - 3 = 9.

When is range used?

Range is typically used when comparing different data sets or in situations where you want to quickly get an idea of the spread of the data. It's especially useful when you want to quickly understand how much difference there is between the extremes of your data.

For example, in science, range can describe the changes in temperature over a week. In sports, it can represent the spread of points scored by different teams. In everyday life, you can use range to describe the difference between the highest and lowest prices of items when shopping.

Range limits

Although this threshold is a simple measure, it still has its limitations:

  • Sensitivity to outliers: Since the range considers only the largest and smallest values, a single extreme value (outlier) can affect it substantially.
  • No information on distribution: This range does not provide information about how the data points are distributed between the minimum and maximum values.
  • Non-descriptive: It is not a comprehensive measure of variability as it ignores all data points other than the two extremes.

Improve understanding with examples

Example 3: Daily temperature

Let us consider the following temperatures recorded in a week:

12°C, 14°C, 15°C, 13°C, 19°C, 17°C, 16°C

Step 1: The minimum temperature is 12°C.

Step 2: The maximum temperature is 19°C.

Step 3: Therefore, the limit is:

Range = 19°C - 12°C = 7°C

The change in temperature for the week is 7°C.

Example 4: Height of plants

Let's hypothetically measure the height of five plants:

34 cm, 45 cm, 40 cm, 33 cm, 44 cm

Step 1: The smallest plant is 33 cm.

Step 2: Tallest plant 45 cm.

Step 3: The range of their heights is:

Range = 45 cm - 33 cm = 12 cm

In this case, the height extends to the range of 12 cm.

Conclusion

Understanding the range of a data set is fundamental to identifying the variability within that data. Whether we are dealing with numbers, scores, prices, or any form of data points, calculating the range can provide quick insight into the spread of information. However, while the range provides important information, it should be considered alongside other measures of the data, such as the mean or median, to better understand the entire dataset.


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