# StudySquare

# Graphs and plots for OCR GCSE Maths

This page covers the following topics:

1. Time series

2. Scatter graphs

3. Box plots

4. Pictograms

5. Histograms

Time series graphs are used to represent data collected over time.

Scatter graphs use a line of best fit, drawn centrally through the points, to show correlations between variables; extend the line to extrapolate (estimate) values outside the range of data given.

Box plots visually display the median, quartiles and interquartile range of a data set against a scale.

Pictograms display data using symbols that makes information visually easier to understand and uses a key to show what each symbol presents. Below is an example displaying the number of cupcakes sold each day at a cafe.

Histograms are used when class intervals are unequal. Frequency is represented by the area of the bar; the height of each bar is called the frequency density and there are no gaps between the bars.

# 1

Ben constructs this box plot to display the 400m and 600 run times of his classmates. State 2 comparisons you can make between the two sets of data.

Possible answers include: the class takes longer to run 500m; the range of times for running 500m is larger than for 400m; the interquartile range for running 500m is larger than for 400m so the times are more spread out for 500m.

# 2

A study surveys some families and constructs a histogram of how much they each spend on food in a week. 20 families spend between £20-£30. Estimate how many families spend over £40.

From the information in the question the frequency density scale is marked with increments of 0.5 (since the frequency density of £20-£30 = 2) so 35 families spend over £40.

# 3

This list shows the number of hours per day Aaron spends on his homework over 10 days: 3, 2.5, 0.5, 2, 2.75, 2, 3.5, 1, 2, 2.5. Construct a box plot of the data.

image

# 4

This pictogram shows the number of fish in different tanks in an aquarium; what is the average number of fish in a tank?

32 fish

# 5

This table below shows the distance (d) a group of students has walked on a particular day. Use it to draw a histogram.

Distance (km), Frequency;

0 < d ≤ 0.5, 5;

0.5 < d ≤ 1.5, 15;

1.5 < d ≤ 2.5, 20;

2.5 < d ≤ 4, 11.

image

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