Chapter 7: Problem 95
For exercises 95-97, evaluate. $$ \frac{5}{21}+\frac{2}{21} $$
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Chapter 7: Problem 95
For exercises 95-97, evaluate. $$ \frac{5}{21}+\frac{2}{21} $$
These are the key concepts you need to understand to accurately answer the question.
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For a fixed length of household copper wire, the relationship of the cross- sectional area, \(x\), and the resistance, \(y\), is an inverse variation. When the cross-sectional area is \(3.14 \times 10^{-6} \mathrm{~m}^{2}\), the resistance is \(5.4 \times 10^{-3} \mathrm{ohm}\). a. Find the constant of proportionality, \(k\). Use scientific notation. Include the units of measurement. b. Write an equation that represents this relationship. c. Find the resistance when the cross-sectional area is \(2.05 \times 10^{-6} \mathrm{~m}^{2}\). Round the mantissa to the nearest tenth.
For exercises 43-58, (a) solve. (b) check. $$ \frac{2}{x}=0 $$
For exercises \(67-82\), use the five steps and a proportion. In 2010 , about \(2,465,940\) Americans died. Find the number of Americans who died without a will. Round to the nearest hundred. (Source: www.cdc.gov, Jan. 11, 2012) Seven out of ten Americans die without a will. (Source: extension.umd.edu)
Explain why the relationship of the number of square feet of carpet that need to be vacuumed, \(x\), and the amount of time it takes to vacuum the carpet, \(y\), is a direct variation.
MRI scans of women with the BRCA1 and BRCA2 genetic mutations that were positive for cancer were wrong five out of six times. (These results are "false positives.") If 1500 women with these mutations had MRI scans that indicated cancer, predict how many of these women did not have cancer. (Source: www.telegraph .co.uk, March 26, 2008)
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