The length and width of a rectangular plate are measured to be 15.3 mm and 12.50 mm. Find the area of the plate up to an appropriate number of significant figures:
Correct answer: A. 191.25 mm2
- A. 191.25 mm2
- B. 195.8 mm2
- C. 196 mm2
- D. 200 mm2
Explanation
The following is the solution:Here are the "significant figure" rules: When adding or subtracting quantities, the sum/difference should be rounded to the number of decimal places as the term with the fewest number of decimal places. When multiplying or dividing, the answer =15.3 x 12.50= 191.25 mm2Since the width (12.50) is in 4 sig figures and the length (15.3) is in 3 sig figs the answer should be rounded off according to the least number of significant figures which is 3, which would give us 191 but since that isn't given in the options our only option is A. The rest of the options are completely wrong as 191.25 cannot be rounded off to any of the mentioned numbers according to the significant figures in the given values in the question.
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About Measurements
Physical quantities are expressed with SI base and derived units, while measurement limits are described through accuracy, precision, absolute and percentage error, and significant figures. Dimensional analysis checks equations, derives relationships and detects inconsistent units, but it cannot determine numerical constants or distinguish quantities with identical dimensions.
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