Chapter 4: Problem 7
Solve the exponential equation. Round to three decimal places, when needed. $$10^{x}=1000$$
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Chapter 4: Problem 7
Solve the exponential equation. Round to three decimal places, when needed. $$10^{x}=1000$$
These are the key concepts you need to understand to accurately answer the question.
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Solve each exponential equation. $$ 2^{x-1}=10 $$
The spread of a disease can be modcled by a logistic function. For example, in carly 2003 there was an outbreak of an illness called SARS (Severe Acute Respiratory Syndrome) in many parts of the world. The following table gives the total momber of cases in Canada for the wecks following March 20,2003 (Source: World Health Organization) (Note: The total number of cases dropped from 149 to 140 between weeks 3 and 4 because some of the cases thought to be SARS were reclassified as other discases.) $$\begin{array}{|c|c|}\hline\text { Weeks since } & \\\\\text { March } 20,2003 & \text { Total Cases } \\\0 & 9 \\\1 & 62 \\\2 & 132 \\\3 & 149 \\\4 & 140 \\\5 & 216 \\\6 & 245 \\\7 & 252 \\\8 & 250 \\\\\hline\end{array}$$ (a) Explain why a logistic function would suit this data well. (b) Make a scatter plot of the data and find the logistic function of the form \(f(x)=\frac{\epsilon}{1+a \varepsilon^{-1}}\) that best fits the data. (c) What docs \(c\) signify in your model? (d) The World Health Organization declared in July 2003 that SARS no longer posed a threat in Canada. By analyring this data, explain why that would be so.
The following table gives the price per barrel of crude oil for selected years from 1992 to 2006 (Source: www.ioga.com/special/crudeoil-Hist.htm) $$\begin{array}{|c|c|}\hline\text { Year } & \begin{array}{c}\text { Price } \\\\\text { (dollars) }\end{array} \\\\\hline 1992 & 19.25 \\\1996 & 20.46 \\\2000 & 27.40 \\\2004 & 37.41 \\\2006 & 58.30\\\ \hline\end{array}$$ (a) Make a scatter plot of the data and find the exponential function of the form \(P(t)=C a^{t}\) that best fits the data. Let \(t\) be the number of years since 1992 (b) Using your model, what is the projected price per barrel of crude oil in \(2009 ?\)
The graph of the function \(f(x)=C a^{x}\) passes through the points (0,12) and (2,3). (a) Use \(f(0)\) to find \(C.\) (b) Is this function increasing or decreasing? Explain. (c) Now that you know \(C\), use \(f(2)\) to find \(a\). Does your value of \(a\) confirm your answer to part (b)?
Solve the logarithmic equation and eliminate any extraneous solutions. If there are no solutions, so state. $$\log (2 x+5)+\log (x+1)=1$$
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