Number And Algebra - Chapter 7 Applying Ratios And Rates - Nelson Think Math Page 22
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32N E L S O N T H I N K M A T H S
8
A u s t r a l i a n C u r r i c u l u m
for the
Example
17
This is a scale drawing of a freshwater microorganism called a Paramecium.
Scale 500 : 1
a
How long is the Paramecium in the scale drawing?
b
How long is the real Paramecium?
The tip of a ballpoint pen is about 0.6 mm wide.
c
How wide would such a pen tip be at the same scale?
d
Would a marble, a cricket ball or a basketball be the best object to show the size of a pen
tip using this scale?
Solution
a
Measure the length.
The Paramecium is 10 cm long in the
drawing.
b
The scale is 500 : 1.
500 mm in the drawing ¼ 1 mm in the
Paramecium
Divide length by 500.
Length of Paramecium ¼ 10 cm 4 500
Convert to mm.
¼ 100 mm 4 500
Calculate.
¼ 0.2 mm
c
Write the scale.
Drawing width : Real width ¼ 500 : 1
This means that the width is 500
times greater in the drawing.
Pen tip in drawing ¼ 0:6 mm 3 500
Pen tip measurement 3 500.
¼ 300 mm
Convert to cm.
¼ 30 cm
d
Compare the diameters.
The basketball would be the best object to
show the size.
259
9780170214148
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