[USMA:30351] RE: rule of thumb

[Bill Potts]

John:   Simple arithmetic tells us that, if a meter is about 10% greater than a yard, a square meter cannot also be 10% greater than a square yard. (A meter is actually a little over 9% greater than a yard.)   10% greater means that the ratio is 1.1. 1.1 squared is 1.21. Thus, on that basis, a square meter is about 20% greater than a square yard. A cubic meter is about 30% greater than a cubic yard.    Beware, though, of multiplying approximations. One should generally calculate using more or less exact values and then round the result.   The exact ratio of meter to yard is 100/(36 x 2.54), which is 1.0936 (when rounded to four decimal places). 1.0936 squared is 1.19 (if we round to two decimal places). 1.0936 cubed is 1.31 (again rounded). If we want to be picky, we can say that a square meter is 19% greater than a square yard and that a cubic meter is 31% greater than a cubic yard, but 20% greater (1.2 times as great) and 30% greater (1.3 times as great) are close enough for quick mental estimation.   For progressives like us, though, the more important ratio is of the yard to the meter (i.e., the reciprocal of the above values). That allows us to estimate how many linear (or square or cubic) meters we're getting when someone provides us with the value in linear (or square or cubic) meters.   1 meter = 0.9144 yards (exactly), meaning you multiply the length in yards by about 0.9 to get the length in meters.   1 square meter =  0.8361 square yards (not exactly), meaning you multiply the area in square yards by about 0.84 to get the area in square meters.   1 cubic meter = 0.7646 cubic yards (not exactly), meaning you multiply the volume in square yards by about 0.76 to get the volume in cubic meters. (For an easier, if less precise, calculation, multiply by 3 then divide by 4.)  Bill Potts, CMS Roseville, CA http://metric1.org [SI Navigator]       -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]On Behalf Of john mercer Sent: Saturday, July 10, 2004 08:52 To: U.S. Metric Association Subject: [USMA:30345] rule of thumb Hello could someone please tel me if a square meter is approx 10% larger than a square yd? I have heard that another rule of thumb is that a meter is approx 10 % longer than a yd.  A yd plus 10 % is 39.36 in. A meter is 10 % longer than a yd minus .23 of an inch.  Close enough for every day use.