Salam Academy
Papers 1F, 2F · Module

Statistics and probability

7 subtopics≈ 205 min in total
  1. Collecting data and stem-and-leaf diagrams

    Data is qualitative (words) or quantitative (numbers); numbers are discrete (counted) or continuous (measured). A fair sample represents the whole population without bias. Frequency tables and stem-and-leaf diagrams organise raw data so you can read off the median, mode and range.

    ≈ 25 min
  2. Averages and range

    The mean shares the total equally, the median is the middle value in order, and the mode is the most common. The range measures spread. For frequency tables, multiply each value by its frequency; for grouped data, use the class midpoints.

    ≈ 30 min
  3. Charts, tables and scatter diagrams

    A pie chart shares 360∘360^\circ in proportion to the frequencies. A two-way table splits a group by two features at once. A scatter diagram shows whether two quantities are related, and a line of best fit lets you estimate one from the other within the range of the data.

    ≈ 30 min
  4. Cumulative frequency

    Cumulative frequency is a running total. Plot it against the upper class boundaries and join the points to get an S-shaped curve. Read across at n2\tfrac n2 for the median, and at n4\tfrac n4 and 3n4\tfrac{3n}4 for the quartiles. The interquartile range is the spread of the middle half.

    ≈ 30 min
  5. Single events and relative frequency

    When outcomes are equally likely, probability =favourable outcomestotal outcomes=\dfrac{\text{favourable outcomes}}{\text{total outcomes}}. The probabilities of all outcomes add to 11, so P(not A)=1−P(A)P(\text{not }A)=1-P(A). When you can't count outcomes, estimate the probability from experiments: relative frequency.

    ≈ 25 min
  6. Combined events and tree diagrams

    For two independent events, multiply ("and"). For mutually exclusive outcomes, add ("or"). A tree diagram organises both: multiply along each route, then add the routes you want. For "at least one", use 1−P(none)1-P(\text{none}).

    ≈ 35 min
  7. Without replacement and Venn diagrams

    When an item is not put back, the second pick has one fewer item, and possibly one fewer of the colour you took. A Venn diagram sorts a group into "only AA", "both", "only BB" and "neither": fill in the overlap first.

    ≈ 30 min