Concept explainers
Spreading of a Disease Jack and Diane live in a small town of 50 people. Unfortunately, both Jack and Diane have a cold. Those who come in contact with someone who has this cold will themselves catch the cold. The data that follow on the next page represent the number of people in the small town who have caught the cold after
Using a graphing utility, draw a
Using a graphing utility, build a logistic model from the data.
Graph the function found in part (b) on the scatter plot.
According to the function found in part (b), what is the maximum number of people who will catch the cold?
In reality, what is the maximum number of people who could catch the cold?
Sometime between the second and third day,
How long will it take for
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Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (4th Edition)
- Running 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_forwardPopulation The population P (in millions) of Italy from 2003 through 2015 can be approximated by the model P=57.59e0.0051t, where t represents the year, with t=3 corresponding to 2003. (Source: U.S. Census Bureau) (a) According to the model, is the population of Italy increasing or decreasing? Explain. (b) Find the populations of Italy in 2003 and 2015. (c) Use the model to predict the populations of Italy in 2020 and 2025.arrow_forwardMaking Ice Our ice machine is making ice in preparation for the game that starts at 7:00 p.m. The machine is monitored, and the amount of ice is recorded at the end of each hour. The results are in the table below. Time 12:00 p.m. 1:00 p.m. 2:00 p.m. 3:00 p.m. Pounds of ice 200 273 346 419 a. Show that the data are linear. b. Let t denote the time in hours since noon, and let I denote the pounds of ice made. Find a linear model for I as a function of t. c. If 675 pounds of ice will be needed for the game tonight, will the ice machine produce enough ice by game time?arrow_forward
- Population The population P (in millions) of Italy from 2003 through 2015 can be approximated by the model P=57.59e0.0051t, where t represents the year, with t=3 corresponding to 2003. (a) According to the model, is the population of Italy increasing or decreasing? Explain. (b) Find the populations of Italy in 2003 and 2015. (c) Use the model to predict the populations of Italy in 2020 and 2025.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 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_forwardpH of Saliva The pH of saliva is normally in the range of 6.4 to 7.0. However, when a person is ill, the persons saliva becomes more acidic. a When Marco is sick, he tests the pH of his saliva and finds that it is 5.5. What is the hydrogen ion concentration of his saliva? b Will the hydrogen ion concentration in Marcos saliva increase or decrease as he gets better? c After Marco recovers, he tests the pH of his saliva, and it is 6.5. Was the saliva more acidic or less acidic when he was sick?arrow_forward
- Population The population P (in thousands) of Tallahassee, Florida, from 2000 through 2014 can be modeled byp=150.9ekt, where t represents the year, with t=0 corresponding to 2000. In 2005, the population of Tallahassee was about 163,075. (a) Find the value of k. Is the population increasing or decreasing? Explain. (b) Use the model to predict the populations of Tallahassee in 2020 and 2025. Are the results reasonable? Explain. (c) According to the model, during what year will the population reach 200,000?arrow_forwardDraw a scatter plot for the data in Table 3. If we wanted to know when the population would reach 15,000,would the answer involve interpolation or extrapolation?arrow_forwardWeight Versus Height The following data show the height h, in inches, and weight w, in pounds, of an average adult male. h 61 62 66 68 70 72 74 75 w 131 133 143 149 155 162 170 175 a Make a power model for weight versus height. b According to the model from part a, what percentage increase in weight can be expected if height is increased by 10?arrow_forward
- 3.4 SKILL BUILDING EXERCISES Using the Regression Line In Exercises S-1 through S-4, you are asked to provide information using the given regression line. Utility Bill The regression line for a data set showing the monthly utility bill U in a certain city versus the square footage F of the residence is given by U=0.2F-100 dollars. What monthly utility bill would be expected for a 25400-square-foot home in this city?arrow_forwardGraphing Discrete Data Plot the data from the table in Exercise S-2. S-2. Testing Data for Linearity Test the following data to see whether they are linear. x 2 4 6 8 y 12 17 21 25arrow_forwardFurther Verification of Newtons Second LawThis exercise represents a hypothetical implementation of the experiment suggested in the solution of part 6 of Example 3.7. A mass of 15 kilograms was subjected to varying accelerations, and the resulting force was measured. In the following table, acceleration is in meters per second per second, and force is in newton. Acceleration Force 8 120 11 165 14 210 17 255 20 300 a. Construct a table of differences and explain how it shows that these data are linear. b. Find a linear model for the data. c. Explain in practical terms what the slope of this linear model is. d. Express, using functional notation, the force resulting from an acceleration of 15 meters per second per second, and then calculate that value. e. Explain how this experiment provides further evidence for Newtons second law of motion.arrow_forward
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