Example – G rouped data Waiting times 1 - 45 - 910 - 1415 - 1920 - 2930 - 3940 - 4950 + frequency91520152011100 Question: Waiting times, to the nearest minute, at a doctors surgery for 100 patients were recorded: Answer: Estimate the median and interquartile range of waiting times The Q3 value is the 3/4 th value: n/4 = 100/4 = 75 th value Q3 lies in class 20 - 29 Q1 = 9.75
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