WJEC Maths for AS: Applied sample

2 Data presentation and interpretation 24 Cumulative frequency diagrams have a running total of the frequency (called the cumulative frequency) on the vertical axis and the quantity you want information about on the horizontal axis. Suppose you have the following table showing the average distance in miles travelled on a full charge for a random sample of 200 electric cars. Notice the classes for the variable which here is the number of miles travelled ( d ). Average distance travelled per charge ( d miles) Frequency 0 ≤ d < 50 3 50 ≤ d < 100 31 100 ≤ d < 150 60 150 ≤ d < 200 84 200 ≤ d < 250 22 We start by adding a running total of the frequency, called cumulative frequency to the table. Average distance travelled per charge ( d miles) Frequency Cumulative frequency 0 ≤ d < 50 3 3 50 ≤ d < 100 31 34 100 ≤ d < 150 60 94 150 ≤ d < 200 84 178 200 ≤ d < 250 22 200 We now plot the graph with ‘average distance travelled per charge’ on the x -axis and ‘cumulative frequency’ on the y -axis. We use the higher value of each class (or group) with its corresponding cumulative frequency. 200 180 160 140 120 100 80 60 40 20 0 0 50 100 150 200 250 Average distance travelled per charge (miles) Cumulative frequency Cumulative frequency graph showing miles per charge for electric cars × × × × ×