On 2008/06/21, at 7:50 AM, Bill Hooper wrote:
Dear Bill,
I have written a thought are in the middle of your email, below.
On Jun 20 , at 3:27 AM, Bill Potts wrote:
Rules of thumb for rough estimates
A meter is about 10% more than a yard.
A square meter is about 20% more square yard.
A cubic meter is about 30% more than a cubic yard.
Let's check it ...
Once in a while it is a good idea to check our "rough estimates"
against the exact figures, just to see if our rough estimates are
sufficiently close to the exact values.
Here are my results of more-or-less exact calculations.
One metre is 9.36% larger than one yard (close to 10%).
One square metre is 19.60% larger than one square yard (close to 20%).
One cubic metre is 30.78% larger than a cubic yard (close to 30%).
It looks like the "rough estimates" are really pretty close to being
exact!
My calculations are below.
Regards,
Bill Hooper
Fernandina Beach, Florida, USA
This looks a lot like the 10 - 11 - 12 - 13 rule that I used to use*.
It goes like this:
10 metres = 11 yards
10 square metres = 12 square yards
10 cubic metres = 13 cubic yards
* When I believed that conversion was a useful option in a metric
transition. I no longer believe that this is true, see http://www.MetricationMatters.com/metric_conversion.html
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SImplification Begins With SI.
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One yard equals 0.9144 m,
so a metre is 0.0856 m larger than 1 yard.
(1.0000 m - 0.9144 m = 0.0856 m)
Therefore, the percent difference compared to the yard is 9.36%.
(0.0856 m / 1 yard = 0.0856 m / 0.9144 m = 0.0936 = 9.36%)
One square yard equals (0.9144 m) squared = 0.8361 m^2.
so a square metre is 0.1639 m^2 larger than a square yard.
(1.0000 m^2 - 0.8361 m^2 = 0.1639 m^2)
Therefore, the percent difference compared to a yard is 19.60%.
(0.1639 m^2 / 1 sq.yd. = 0.1639 m^2 / 0.8361 m^2 = 0.1960 =
19.60%)
One cubic yard equals (0.9144 m) cubed = 0.7646 m^3
so a cubic metre is 0.2354 m^3 larger than a cubic yard.
(1.0000 m^2 - 0.7646 m^3 = 0.2354 m^3)
Therefore, the percent difference compared to a cubic yard is 30.78%.
(0.2354 m^3 / 1 cu.yd. = 0.2354 m^3 / 0.7646 m^3 = 0.3078 =
30.78%.)
Cheers,
Pat Naughtin
PO Box 305 Belmont 3216,
Geelong, Australia
Phone: 61 3 5241 2008
Metric system consultant, writer, and speaker, Pat Naughtin, has
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