Significant figures estimating

Flux (a) Deforestation rate Original forest mass 1.9 X 10V 400 Mg ha l INPE (1998), average for 1992-1996 One significant figure estimate, based on other estimates 464 Mg ha l Feamside (1997), 424 Mg ha" Brown et al. (1992)... 

The numerator, therefore, is 23.41 0.028 (note that we retain an extra significant figure since we will use this uncertainty in further calculations). To complete the calculation, we estimate the relative uncertainty in Ca using equation 4.7, giving... 

For releases to any medium that amount to 1,000 pounds or more forthe year, you must provide an estimate in pounds per year in column A.2. Any estimate provided in column A.2 should be reported to no more than two significant figures. This estimate should be in whole numbers. Do not use decimal points. 

Each time you inhale, you take in about 500 mL (two significant figures) of air, each milliliter of which contains 2.5 X 1019 molecules. In delivering the Gettysburg Address, Abraham Lincoln is estimated to have inhaled about 200 times. 

Although several figures in Table IV are significant, the estimates are probably accurate to the first digit at best. However, they do suggest that widespread but low-level exposures from automobiles and service stations provide the majority of benzene molecules that enter human bodies. Whether these are the most biologically significant emissions depends on the behavior of dose-response relationships at low dose levels. 

Estimates are based on a wet soil density of 1.8 tons/yd (2.1 tons/m ) based on SITE demonstration results. Costs based on contaminated soil treated. AU costs are rounded to two significant figures, based on the sum of the individual costs before rounding. 

Significant figures are the digits in any measured value that are known with certainty plus one final digit that is estimated and hence uncertain. 

Estimated standard deviations in the least significant figure(s) are given in parentheses in this and all subsequent tables. 

Positional and anisotropic parameters are given x 10. Numbers in parentheses are the estimated standard deviations in the units of the least significant figure given for the corresponding parameter. The anisotropic temperature factor is expl-tB h2 + B22-2 + e33 -2 + + gi3hA + 23 1 ... 

Bond lengths/A, estimated standard deviations in parentheses refer to the least significant figure(s) ... 

This example involves concepts and units which may be unfamiliar to you, so that you can t easily judge whether the result "makes sense," so we ll check the answer by estimation. Write each term in exponential notation, using just one significant figure. Then mentally combine the powers of 10 and the multipliers separately to estimate the result ... 

The estimate agrees with the calculation to one significant figure, showing that the calculation is very likely correct. 

In elementary measurements in chemistry and physics, the last digit is an estimated figure and is considered as a significant figure. 

The answer should be rounded off after adding or subtracting, so as to retain digits only as far as the first column containing estimated figures. (Remember that the last significant figure is estimated.)... 

Calculated by difference ranges are set by combinations of the low and high denitrification estimates (which lead to high or low estimates of autochthonous organic C) and upper and lower estimates of burial. Values have been rounded to two or three significant figures. 

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