Representing numbers graphically: Fractions. |
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4th year of secondary education - Section B | |
Representing fractions | ||
A positive fraction
is known as a proper fraction (or simple fraction) when its numerator is
less than its denominator. The fraction is a number which lies between 0 and 1.
For example, 2/3 and 3/4 are proper fractions. A positive fraction is known as an improper
fraction for the opposite reason, (i.e.) when the numerator is greater than the
denominator. The fraction is a number greater than or equal to 1.
For example, 5/3 and 9/4 are improper fractions. Imagine
we want to illustrate the number 3/4 on a straight line. As it is a proper
fraction, it will be found somewhere between 0 and 1. We have to divide the unit
segment (0-1) into four parts and count three starting from 0. | ||
4. Illustrate the number 3/4
in your exercise book. Follow the instructions below using set squares and your
compass to divide the unit segment into four equal parts:
Draw a horizontal line. Label the end on the left
with the number 0 and the right end with the number 1. This will be our
unit segment.
Draw a longer line from 0 which is not horizontal.
Use a compass to mark four equal divisions on this
line starting from 0.
Use a ruler to draw a line connecting the last mark
made by the compass on the line and point 1.
Use your set squares to draw lines parallel to this
segment from the other three marks made by the compass.
The points where these parallel lines cut the horizontal
segment divide the segment into four equal parts.
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Look carefully at the drawing in the window to see what the drawing in your
exercise book should look like.
Repeat the exercise to illustrate the following numbers: 4/5,
5/6 and 2/7. Use
the window to check that your drawing is correct. | ||
Remember that an improper
fraction can always be broken down into a whole number plus a proper fraction. For
example,
13/5 = 2 + 3/5,
where 2 is the whole
number we get when we divide 13 by 5, and 3 is the remainder. Therefore, the number 13/5 is located somewhere
between the numbers 2 and 3. In order to illustrate the number 13/5 we need to
illustrate the number 3/5 in the segment [2,3]. In other words, we have to
divide the segment [2,3] into 5 parts and count 3 parts starting from number 2. | ||
5. Follow the instructions given above to illustrate the number 13/5 in your exercise book. Then, check that your drawing is correct by comparing it with the one in the following window. | ||
Look carefully at the
drawing in the window to see what the drawing in your exercise book should look
like.
Illustrate the following numbers in the same way: 10/3,
13/2, 17/5 and 9/4.
Use this window to check your results. |
Fernando Arias Fernández-Pérez | ||
Spanish Ministry of Education. Year 2001 | ||
Except where otherwise noted, this work is licensed under a Creative Common License