Data Analysis

Mean, Median, Mode, Range

Data set: 4, 7, 7, 9, 13

• Mean (average): sum ÷ count = (4+7+7+9+13)/5 = 40/5 = 8
• Median (middle): put in order, pick the middle value = 7
• Mode (most frequent): 7 appears twice → mode = 7
• Range: max − min = 13 − 4 = 9

Reading Graphs

• Bar graph: compare categories — read the height/length of each bar against the axis.
• Line graph: shows change over time — slope up = increase, slope down = decrease.
• Pie chart: shows parts of a whole — percentages should add to 100%.

Tip: Always check the axis labels and scale before answering.

Probability

Probability = (number of favourable outcomes) ÷ (total number of outcomes)

Always between 0 (impossible) and 1 (certain).

Example: A bag has 3 red and 5 blue marbles. P(red) = 3/8.

P(not red) = 1 − P(red) = 1 − 3/8 = 5/8.