Statistics in WAEC: Mean, Median, Mode and Beyond

Statistics questions in WAEC consistently yield high marks for prepared students and lost marks for those who rush. The three measures of central tendency — mean, median, and mode — are just the beginning. The mean is the sum of all values divided by the count. For grouped data, use the midpoint of each class interval multiplied by its frequency, sum those products, and divide by total frequency. The median is the middle value when data is ordered. For grouped data, use the formula: L + ((n/2 − F) / f) × h, where L is the lower class boundary, F is the cumulative frequency before the median class, f is the frequency of the median class, and h is the class width. Practise identifying the correct formula from the question wording. Mode is the most frequent value — straightforward for raw data, but modal class for grouped data. Beyond averages, WAEC tests standard deviation, cumulative frequency curves (ogives), histograms, and bar charts. Always label axes and title your graph — unlabelled graphs lose presentation marks.