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Home > Maths I > Relationships > Interpreting graphs

Maths I

Interpreting graphs

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Introduction

It is important that when we have a graph we actually find it useful and can take information from it. First of all lets look at some misleading or badly-drawn graphs.

Use of scales on graph axes

Two line graphs, both comparing current in m a along the x axis with voltage in volts up the y axis. The first graph goes up to 50ma and 150 volts, and the straight line goes up to 23 or so ma and 90 volts. The second grap goes up to 30ma and 40 volts, with the straight line reaching near both these values. Both lines start at the zero point.

In the diagram above the scale on the left-hand-side graph is inappropriate. The numbers go up unnecessarily high on both axes which means the points are squashed into just a small part of the graph area. The scale on the right-hand-side graph is much more suitable. Because the scale suits the information the points fill the whole of the sheet making it clearer to read.

A grid for a potential graph, comparing current along the x axis with voltage up the y axis. The current goes from zero m a to 34, and the voltage goes from zero volts to 40 volts.

In the graph above the numbers on the bottom axis are unequal. This is wrong and makes the graph difficult to read.

Scales should either start at zero, or be concertinaed (squashed) as shown in the y-axis in the above graph.

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Bar graph.

Class Clips

Video clip showing how a clothes shop uses graphs to keep track of stock and popular sizes

Watch

A young boy playing in his garden.

Class Clips

And just for fun - become as excited about graphs as this boy with this jolly song...maybe!

Play

A picture of Mia Cadaver

Tombstone Timeout

Swot up your sums with Mia Cadaver's maths game

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