Final answer:
When choosing the frequency for a graph on MATLAB, consider the data distribution and select intervals that accurately reflect the number of occurrences. The scale should be neither too large nor too small, facilitating easy trend identification.
Step-by-step explanation:
The frequency of the graph on MATLAB should be chosen based on the distribution of your data across the intervals you have selected. When plotting a frequency polygon, the x-axis typically shows the midpoint for each interval, while the y-axis indicates the frequency of data points within each interval. It's important to choose a frequency that accurately represents the number of data occurrences. For instance, for the interval 49.5-59.5, if there are 5 data values, the point plotted at the midpoint, 54.5, should reflect the frequency value of 5. Similarly, for intervals with no data, like those before 39.5-49.5 and after 99.5-109.5, the frequency value is 0.
In general, it's important to select a scale on the x-axis and y-axis that makes it easy to identify trends and that accurately represents all your data without being too large or too small. This aids in visual interpretation and makes it easier to determine the scaling and distribution of your data. Additionally, the frequency polygon graph should be skewed if the data distribution is skewed, so as to provide an accurate visual representation of the data at hand.