A researcher has grouped 240 waiting times using intervals of widths 2, 3, 5 and 10 minutes. The corresponding frequencies are 24, 54, 90 and 72.
In this question you must show detailed reasoning.
Calculate the frequency densities.
Identify the modal class and explain why comparing frequencies alone could give the wrong modal class for a histogram.
State one limitation of using the histogram to estimate how many waits were below a value inside a class.
121 exam-style questions on OCR A Level Maths 2.2 Data Presentation and Interpretation, covering 2.2.1 Tables and diagrams for single variable data, 2.2.2 Area in a histogram, 2.2.3 Scatter diagrams and regression lines, 2.2.4 Informal interpretation of correlation, 2.2.5 Correlation and causation, 2.2.6 Measures of average and spread, 2.2.7 Calculations of mean and standard deviation, 2.2.8 Outliers, 2.2.9 Selecting or critiquing data presentation, and 2.2.10 Cleaning data. Each one has a worked solution and a mark scheme showing where the marks go.