5.1 Data Interpretation (Grouped Data)

• Frequency distribution tables of grouped data
• Modal class
• Mean and median of grouped data

• determine an appropriate class width for grouping data
• draw frequency distribution tables of grouped data
• identify the modal class of grouped data
• calculate the mean of grouped data from real-life situations
• determine the median of grouped data from real-life situations
• appreciate data interpretation in real-life situations

“How do we interpret data?”

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1. Grouping data and choosing a class width
   40 min · 1 practice tasks · quiz
   Divide the range by the number of classes you want, then round to something tidy.
2. The frequency distribution table
   40 min · 1 practice tasks · quiz
   Tally each value into its class, count the tallies, and check the total.
3. The modal class
   40 min · 1 practice tasks · quiz
   The class with the highest frequency, and it is a class rather than a single value.
4. The mean of grouped data
   40 min · 1 practice tasks · quiz
   Treat every value in a class as sitting at the midpoint, then take a weighted average.
5. The median of grouped data
   40 min · 1 practice tasks · quiz
   Cumulative frequency finds the median class; interpolation finds where in it the middle value falls.
6. Choosing and interpreting an average
   40 min · 1 practice tasks · quiz
   Mode, mean and median answer different questions, and the wrong choice misleads honestly.