2 interactive labs · AS & A Level Mathematics 9709
Histograms and Frequency Density
5.1 Representation of data · Classes of unequal width: predict whether the tallest bar holds the most values, then set frequencies or bar heights and read each frequency from the area.
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About this lab
Classes of unequal width: predict whether the tallest bar holds the most values, then set frequencies or bar heights and read each frequency from the area.
You will be able to
Calculate the frequency density of each class as frequency ÷ class width, and draw each bar to that height.
Determine the frequency of a class from its bar as frequency density × class width, and compare the number of values in classes of unequal width.
Estimate the number of values in an interval that is not a whole class from the matching part of the area, stating the assumption of even spread.
Explain why plotting frequency instead of frequency density misrepresents a wide class.
Summarising and Comparing Two Data Sets
5.1 Representation of data · Predict which of two sets has the larger mean, then find the mean and σ from totals or coded totals, read the box plots and compare the sets in words.
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About this lab
Predict which of two sets has the larger mean, then find the mean and σ from totals or coded totals, read the box plots and compare the sets in words.
You will be able to
Calculate the mean and standard deviation of a set of data from the list, from Σx and Σx², or from coded totals Σ(x − a) and Σ(x − a)², and use grouped data with class midpoints.
Determine the median, quartiles and interquartile range from a list or from grouped data (stating the quartile method used), and the range from a list; grouped data gives only an upper bound for the range.
Compare two data sets on box-and-whisker plots by naming an average and a measure of spread, in context.
Describe the limitations of estimates from grouped data and explain why the mean is affected by an extreme value but the median is not.
