📊 Unlocking Averages: Mastering Mean, Median, Mode & Range!

Ever wondered how teachers summarise an entire class’s test scores in just a few numbers? Measures of central tendency and spread give us quick snapshots of data, helping us spot trends and outliers. Mastering these concepts is **essential** for O Level exams and for interpreting everyday statistics you meet in news, sports, and science.

Main Concept: The "Big 4" of Data

The **mean**, **median**, **mode**, and **range** each tell us something different about a data set. Knowing when to use each measure—and how to calculate them reliably—will earn you marks in both Paper 1 and Paper 2 questions.

Mean: Add all values and divide by the number of values $n$ .
Range: Highest value $-$ Lowest value (shows spread).

Worked Example: Analysing Quiz Scores

Problem: The scores out of 12 for eight students are 5, 7, 8, 9, 9, 10, 12, 12. Find the mean, median, mode, and range.

Step 1:
$\bar{x}=\dfrac{5+7+8+9+9+10+12+12}{8}=\dfrac{72}{8}=9$
Step 2: Ordered data are already given. Median is the average of 4th and 5th terms
$\dfrac{9+9}{2}=9$
. Mode = 9 & 12 (both appear twice). Range =
$12-5=7$
.

Practice applying these four measures to different data sets until the steps become automatic. With consistent effort, you’ll boost both your confidence and your exam performance—happy calculating!