Frequency Table and Median - JSS1 Mathematics Lesson Note

Frequency Table:

A frequency table summarizes categorical or grouped numerical data by showing the number of occurrences in each category. It helps in organizing data for easier analysis and understanding. For example, if we have data on the number of cars passing a point each hour:

Time (hours)      Frequency

8-9          20

9-10       25

10-11     15

11-12     30

This frequency table shows how many cars passed during each hour interval.

Median:

The median is a measure of central tendency that represents the middle value in a sorted, ascending or descending, list of numerical data. It's useful because it's less affected by extreme values (outliers) than the mean. To find the median from a frequency table, you typically arrange the data and then find the middle value. For example, if we have the following set of data:

5, 7, 3, 8, 2, 9, 4, 6, 1

First, sort it:

1, 2, 3, 4, 5, 6, 7, 8, 9

The median here is 5, because it is the middle value. If there is an even number of data points, you take the average of the two middle values.