Concept explainers
Reminder Round all answers to two decimal places unless otherwise indicated.
High School Graduates The following table shows the number, in millions, graduating from high school in the United States in the given year.
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a. Make a plot of the data and explain why a linear model is not appropriate.
b. Use regression to find a linear model for the years
c. Use regression to find a linear model for the years
d. Write a formula for a model of the number, in millions, graduating as a piecewise-defined function using the linear models from part b and part c.
e. Make a graph of the formula you found in part d.
f. The number graduating in
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Chapter 5 Solutions
Functions and Change: A Modeling Approach to College Algebra (MindTap Course List)
- Mortgage Rates The following table is taken from the website of Freddie Mac. It shows rates for 30-year fixed-rate mortgages since 1970. y=Year r=Mortgagerate 1975 9.05 1980 13.74 1985 12.43 1990 10.13 1995 7.93 2000 8.05 2005 5.87 2010 4.69 2015 3.84 a. Explain in practical terms the meaning of r(2003). b. Use the table to estimate the value of r(2003).arrow_forwardDepreciation Once a new car is driven away from the dealer, it begins to lose value. Each year, a car loses 10% of its value. This means that each year the value of a car is 90% of the previous year’s value. If a new car was purchased for $20,000, the value at the end of the first year would be $20000(0.90) and the value of the car after the end of the second year would be $20000(0.90)2. Complete the table shown below. What will be the value of the car at the end of the eighth year? Simplify the expression, to show the value in dollars.arrow_forwardHeart Disease In a certain country, the number of deaths due to heart disease decreased from 235 in one year to 221 in the next year. What percentage decrease in deaths due to heart disease does this represent?arrow_forward
- Running Speed A man is running around a circular track that is 200 m in circumference. An observer uses a stopwatch to record the runner’s time at the each of each lap, obtaining the data in the following table. (a) What was the man’s average speed (rate) between 68 s and 152 s? (b) What was the man’s average speed between 263 s and 412 s? (c) Calculate the man’s speed for cadi lap, Is he slowing down, speeding up, or neither?arrow_forwardRunning Speed A man is running around a circular track that is 200 m in circumference. An observer uses a stopwatch to record the runners time at the end of each lap, obtaining the data in the following table. aWhat was the mans average speed rate between 68 s and 152 s? bWhat was the mans average speed between 263 s and 412 s? cCalculate the mans speed for each lap. Is he slowing down, speeding up or neither? Time s Distance m 32 200 68 400 108 600 152 800 203 1000 263 1200 335 1400 412 1600arrow_forwardMarginal Tax Rate The following table shows tax due for the given taxable income level for a single taxpayer. Taxable income Tax due 97, 000 21, 913 97, 050 21, 927 97, 100 21, 941 97, 150 21, 955 97, 200 21, 969 a. Show that the data in the table are linear. b. How much additional tax is due on each dollar over 97.000? c. What would you expect to be your tax due if you had a taxable income of 97, 000? of 98, 000? d. Find a linear formula that gives your tax due if your income is A dollars over 97, 000.arrow_forward
- DVD Player Sales The table shows the number of DVD players sold in a small electronics store in the years 2003-2013. Year DVD players sold 2003 495 2004 513 2005 410 2006 402 2007 520 2008 580 2009 631 2010 719 2011 624 2012 582 2013 635 aWhat was the average rate of change of sales between 2003 and 2013? bWhat was the average rate of change of sales between 2003 and 2004? cWhat was the average rate of change of sales between 2004 and 2005? dBetween which two successive years did DVD player sales increase most quickly? Decrease most quickly?arrow_forwardUsing the model in Example 6, estimate the number of cases of flu on day 15.arrow_forwardKeplers Third Law According to Keplers third law of planetary motion, the mean distance D, in millions of miles, from a planet in our solar system to the sun is related to the time P, in years, that it takes for the planet to complete a revolution around the sun, and the relationship is D=93P2/3. It takes the planet Pluto 249 years to complete a revolution around the sun. What is the mean distance from Pluto to the sun? What is the mean distance from Earth to the sun? Give your answers to the nearest million miles.arrow_forward
- The Kelvin Temperature Scale Physicists and chemists often use the Kelvin temperature scale. In order to determine the relationship between the Fahrenheit and Kelvin temperature scales, a lab assistant put Fahrenheit and Kelvin thermometers side by side and took readings at various temperatures. The following data were recorded. K = kelvins F = degrees Fahrenheit 200 -99.67 220 -63.67 240 -27.67 260 8.33 280 44.33 300 80.33 a. Show that the temperature F in degrees Fahrenheit is a linear function of the temperature K in kelvins. b. What is the slope of this linear function? Note: Be sure to take into account that the table lists kelvins in jumps of 20 rather than in jumps of 1. c. Find a formula for the linear function. d. Normal body temperature is 98.6 degrees Fahrenheit. What is that temperature in kelvins? e. If temperature increases by 1 kelvin, by how many degrees Fahrenheit does it increase? If temperature increases by 1 degree Fahrenheit, by how many kelvins does it increase? f. The temperature of 0 kelvins is known as absolute zero. It is not quite accurate to say that all molecular motion ceases at absolute zero, but at that temperature the system has its minimum possible total energy. It is thought that absolute zero cannot be attained experimentally, although temperatures lower than 0.0000001 kelvin have been attained. Find the temperature of absolute zero in degrees Fahrenheit.arrow_forwardPsychologists have developed mathematical models to predict memory performance as a function of the number of trials n of a certain task. Consider the learning curve P=0.5+0.9(n1)1+0.9(n1),n0 where p is the fraction of correct responses after n trials. (a) Complete the table for this model. What does it suggest? (b) According to the model, what is the limiting percent of correct responses as n increases?arrow_forwardDVD Player sales The table shows the number of DVD play-ers sold in a small electronics store in the years 2003-2013. What was the average rate of change of sales between 2003 and 2013? Whatwas the average rate of change of sales between 2003 and 2004? What was the average rate of change of sales between 2004 and 2005? Between which two successive years did DVD player sales increase most quickly?arrow_forward
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