 Frequency is the number of times you get an answer This Column Means: How often they do homework Frequency is the number of times you get an answer  How many people are in this ‘class’ How fast they do the homework 1

How Many students do up to 150 hours p.a?  15 10 5 2

A student who does exactly 500 hours p.a. is..  In this class In this class 3

 The cumulative column ‘accumulates’ (adds up) the number of answers Number of people in the survey: 35  The cumulative column ‘accumulates’ (adds up) the number of answers 200 Unknown 4

 Always Plot on the UPPPER LIMIT The first Point will be plotted at: 0 (hours), 5 (frequency) 25 (hours), 5 (frequency) Always Plot on the UPPPER LIMIT  50 (hours), 5 (frequency) 5

 Always Plot the CUMULATIVE frequency The second Point will be plotted at: 50 (hours), 15 (frequency)  150 (hours), 15 (frequency) Always Plot the CUMULATIVE frequency 150 (hours), 10 (frequency) 6

 The line goes through EVERY point On a cumulative frequency diagram (graph) the line should be: The line goes through EVERY point A smooth curve passing close to the points A straight line passing through the middle of the points  Dot to dot OR a smooth curve going through ALL the points 7

The median is  About 600 hours About 500 hours About 100 people 8

Find the median position on the cumulative frequency axis then go down to the x-axis to find the median value The median is  About 600 hours About 500 hours About 100 people 8

 The lower quartile is About 400 hours About 250 hours About 50 people 9

The lower quartile is halfway between the first answer and the median  About 400 hours About 250 hours About 50 people 9

The 90th centile is  About 950 hours Not available About 180 hours 10

The 90th centile means 90% of values are lower than this The 90th centile is  About 950 hours Not available About 180 hours 10

Class widths are normally: The same size  Different sizes Don’t assume the class widths are the same, always look at the upper limit when you plot 11

 Just put numbers on your axes The x-axis should show: Evenly spaced numbers Just put numbers on your axes The class labels (0<t….) 12

Revision Notes Sketch the Cumulative Frequency Diagram of these results Annotate with your notes You need AT LEAST one note for every wrong answer

Frequency is the number of times you get an answer The cumulative column ‘accumulates’ (adds up) the number of answers The line goes through EVERY point The 90th centile means 90% of values are lower than this Always Plot on the UPPPER LIMIT Just put numbers on your axes Always Plot the CUMULATIVE frequency Find the median position on the cumulative frequency axis then go down to the x-axis to find the median value Don’t assume the class widths are the same, always look at the upper limit when you plot