3
The Metric System
Functions
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3.7
Metric and U.S. Conversion
Copyright © Cengage Learning. All rights reserved.
Metric and U.S. Conversion
In technical work, you must sometimes change from one
system of measurement to another.
Most numbers are rounded to three or four significant
digits. Due to this rounding and your choice of conversion
factors, there may be a small difference in the last digit(s)
of the answers involving conversion factors. This small
difference is acceptable.
In this section, round each result to three significant digits,
when necessary.
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Metric and U.S. Conversion
Figure 3.16 shows the relative sizes of each of four sets of
common metric and U.S. units of area.
Relative sizes of some common metric and U.S. units of area
Figure 3.16
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Example 1
Change 17 in. to centimetres.
conversion factor
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Metric and U.S. Conversion
In the U.S. system, the acre is the basic unit of land area.
Historically, the acre was the amount of ground that a yoke
of oxen could plow in one day.
1 acre = 43,560 ft2
1 mi2 = 640 acres = 1 section
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Metric and U.S. Conversion
Land areas in the United States are still typically measured
in the U.S. system.
When converting between metric and U.S. land-area units,
use the following relationship:
1 hectare = 2.47 acres
A good approximation is
1 hectare = 2.5 acres
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