Finding missing values in data is an important skill in statistics. Graphs can really help us see these missing parts clearly. Let’s explore some simple ways to find missing values using different types of graphs.

1. Bar Charts:

   • Bar charts show data with tall rectangular bars. The height of each bar tells us the value it represents.
   • To find a missing value, look at the height of the bar next to it. If the nearby bars are much taller or shorter, you can guess the missing value by averaging the heights of the similar bars.

2. Line Graphs:

   • Line graphs connect dots with lines and are great for showing changes over time.
   • To find a missing value, look at the slope or steepness between the known points. If the graph is showing a steady trend, like going up or down, you can estimate the missing value with a simple formula:
     $(y_2 - y_1) / (x_2 - x_1)$
     Here, $(x_1, y_1)$ and $(x_2, y_2)$ are points we already know.

3. Pie Charts:

   • Pie charts show different parts of a whole, like slices of pizza. Each slice shows a piece of the data.
   • Even though pie charts aren’t the best for finding exact missing values, you can still figure out the missing piece if you know the total. For example, if a pie chart shows sales and one slice is missing, you can find it by subtracting the sum of the known slices from 100%.

By using these simple graphs, Year 8 students can figure out missing values and understand data better.