Question 5: From the graph, approximately what would you estimate the median and the first and third quartiles to be? Where would they appear along the horizontal axis?
The median is the value which divides the distribution into two equal parts. The middle of the distribution looks to be between the two tallest bars, around 1650 mm or perhaps just above.
The first quartile, which cuts off the bottom quarter of the observations, would be around 1600 mm. The third quartile, which cuts off the top quarter of the observations, appears to be around 1700 mm, or just above.
In fact, the median is 1662.5 mm, the first quartile is 1610 mm and the third quartile 1706.5 mm. Of course, it is difficult to judge accurately from the histogram and any answers within 20 mm of the correct one are good.
This is how they look on the histogram:
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Last updated: 31 July, 2006.