Concept explainers
Reminder Round all answers to two decimal places unless otherwise indicated.
Ship Propellers An ideal diameter d, in feet, of a ship's propeller is given by the formula
Here
a. If the horsepower is increased by
b. If the horsepower remains the same while the number of revolutions per minute is increased by
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Chapter 5 Solutions
Functions and Change: A Modeling Approach to College Algebra (MindTap Course List)
- ReminderRound all answers to two decimal places unless otherwise indicated. DensityThe total weight of a rock depends on its size and is proportional to its density. In this context, density is the weight per cubic inch. Let w denote the weight of the rock in pounds, s the size of the rock in cubic inches, and d the density of the rock in pounds per cubic inch. a. What is the total weight of a 3-cubic-inch rock that weighs 2 pounds per cubic inch? b. Write an equation that shows the proportionality relation. What is the constant of proportionality? c. Use the equation you found in part b to find the total weight of a 14-cubic-inch rock with density 0.3 pound per cubic inch.arrow_forwardReminder Round all answers to two decimal places unless otherwise indicated. Driving Under the Influence: The Widmark formula,30 developed in 1932, is used to model the blood alcohol content B at a time t hours after consuming alcohol B=5.14ArW0.015t Here B is the blood alcohol content, W is the weight in pounds, A is the liquid ounces of alcohol consumed, and r is a factor determined by gender 0.73for men and 0.66 for women. Consider the blood alcohol content of a 180-pound man after consuming six 12-ounce cans of beer. a. The beer consumed is 6 alcohol. How many ounces of alcohol were consumed? b. Write a formula that gives the blood alcohol content for this man t hours after consuming the alcohol. Round the first term to three decimal places. c. In most states, driving with a blood alcohol content of 0.08 or higher may result in arrest and severe penalties. During which time period is it unlawful for this man to drive?arrow_forwardReminder Round all answers to two decimal places unless otherwise indicated. Length of Skid Marks Versus Speed When a car skids to a stop, the length L, in feet, of the skid marks is related to the speed S, in miles per hour, of the car by the power function L=130hS2. Here the constant h is the friction coefficient, which depends on the road surface. For dry concrete pavement, the value of h is about 0.85. a. If a driver going 55milesperhour on dry concrete jams on the brakes and skids to a stop. how long will the skid marks be? b. A policeman investigating an accident on dry concrete pavement finds skid marks 230feet long. The speed limit in the area is 60milesperhour. Is the driver in danger of getting a speeding ticket? c This part of the problem applies to any road surface, so the value of h is not known. Suppose you are driving at 60milesperhour, but, because of approaching darkness, you wish to slow to a speed that will cut your emergency stopping distance in half. What should your new speed be? Hint: You should use the homogeneity property of power functions here. By what factor should you change your speed to ensure that L changes by a factor of 0.5?arrow_forward
- Reminder Round all answers to two decimal places unless otherwise indicated. The Fukushima Disaster On March 11, 2011, Japan suffered an earthquake and tsunami that caused a disastrous accident at the Fukushima nuclear power plant. Among many other results, amounts of iodine-131 that were 27 times the government limit were found in a sample of spinach 60 miles away?' Now, 27 times the government limit of iodine-131 is 54 thousand becquerels per kilogram." The following table shows the amount I, in thousands of becquerels per kilogram, of iodine-131 that would remain after t days. t=time,indays I=amountofiodine-131 0 54.00 1 49.52 2 45.41 3 41.64 4 38.18 a. Show that the data are exponential. In this part and the next, round to three decimal places b. Find an exponential model that shows the amount of iodine-131 present after t days. c. How long will it take for the amount of iodine-131 to fall to the government limit of 2 thousand becquerels per kilogram? Round your answer to the nearest whole day.arrow_forwardReminder Round all answers to two decimal places unless otherwise indicated. World Copper Production World production of copper, in millions of tons per year, from 1900 to 2000 is given by C=0.51.033t, where t is the time in years since 1900. a.What production level does this model give for the year 2000? b.If this model were extended to 2025, how could you use your knowledge of copper production in 2024 to estimate copper production in 2025?arrow_forwardReminder Round all answers to two decimal places unless otherwise indicated. Kleibers law states that for the vast majority of animals, the metabolic rate M is a power function of the weight W, and the power is k=34. a.The Eastern gray squirrel weighs about 1 pound. How does the squirrels metabolic rate compare with that of a 200 -pound man? b.How does a 200- pound mans metabolic rate compare with that of a 130- pound woman? c.Based on your answer to part b, would overeating the same amount for each be more likely to lead to weight gain for the man or for the woman?arrow_forward
- Reminder Round all answers to two decimal places unless otherwise indicated. Giants Ants and Spiders Many science fiction movies feature animals such as ants, spiders, or apes growing to monstrous sizes and threatening defenseless Earthlings. Of course, they are in the end defeated by the hero and heroine. biologists use power function as a rough guide to relate body weight and cross-sectional area of limbs to length or height. Generally, weight is thought to be proportional to the cube of length, whereas the cross-sectional area of limbs is proportional to the square of length. Suppose an ant, having been exposed radiation is enlarged to 500 times its normal length. Such an event can occur only in Hollywood fantasy. Radiation is utterly incapable of causing such a reaction. a.By how much will its weight be increased? b.By how much will the cross-sectional area of its legs be increased? c.Pressure on a limb is weight divided by cross-sectional area. By how much has the pressure on a leg of the giant ant increased? What do you think is likely to happen to this unfortunate ant? Note: The factor by which pressure increases is given by . FactorofincreaseinweightFactorofincreaseinarea)arrow_forwardReminder Round all answers to two decimal places unless otherwise indicated. Falling Objects An object is dropped near the surface of a planet. The time T, in seconds, it takes for the object to falls feet is given by the formula T=cs0.5 for some constant c that depends on the planet. a. On Earth, the constant c is 0.25. How long does it take an object to fall 16feet on Earth? b. On a certain planet, an object takes 5seconds to fall 20feet. What is the value of the constant c for this planet? c. If it takes 1second for an objects to fall 10feet on a planet, how long does it take an object to fall 40feet?arrow_forwardReminder Round all answer to two decimal places unless otherwise indicated. Lean Body Weight in Males Your lean body weight L is the amount you would weigh if all the fat in your body were to disappear. One text gives the following estimate of lean body weight L in pounds for young adult males: L=98.42+1.08W4.14A, where W is total weight in pounds and A is abdominal circumference in inches. 7 a. Consider a group of young adult males who have the same abdominal circumference. If their weight increases but their abdominal circumference remains the same, how does their lean body weight change? b. Consider a group of young adult males who have the same weight. If their abdominal circumference decreases but their weight stays the same, how does their lean body weight change? c. Suppose a young adult male has a lean body weight of 144 pounds. Over a period of time, he gains 15 pounds in total weight, and his abdominal circumference increases by 2 inches. What is his lean body weight now?arrow_forward
- Reminder Round all answers to two decimal places unless otherwise indicated. Math and the City An article in The New York Times states, "The number of gas stations in a city grows only in proportion to the 0.77 power of population. This means that the approximate number G of gas stations in a city is a power function of the population N, and the power is k=0.77. That is, G=cN0.77, where c is some as yet unknown constant. We measure N in millions. a. If one city is twice as large as another, how do the numbers of gas stations compare? b. The population of Houston, Texas, is 2.2million and, according to Yahoo Local, there are 1239 gas stations in Houston. Use this information to find the value of c. c. Los Angeles has a population of about 3.9million. Using the value of c that you found in part b, estimate the number of gas stations in Los Angeles. Round your answer to the nearest whole number. Note: According to Yahoo Local, the correct number is 2013.arrow_forwardReminder Round all answers to two decimal places unless otherwise indicated. Sales Growth A study of the sales s, in thousands of dollars, of a product as a function of time t, in years, yields the equation of change dsdt=0.3s(4s). This is valid for s less than 5. a.What level of sales will be attained in the long run? b.What is the largest rate of growth in sales?arrow_forwardReminder Round all answers to two decimal places unless otherwise indicated. Cleaning Contaminated Water A tank of water is contaminated with 60 pounds of salt. In order to bring the salt concentration down to a level consistent with EPA standards, clean water is being piped into tank, and the well-mixed overflow is being collected for removal to a toxic-waste site. The result is that at the end of each hour, there is 22 less salt in the tank than at the beginning of the hour. Let S=S(t) denote the number of pounds of salt in the tank t hours after the flushing process begins. a. Explain why S is an exponential function and find its hourly decay factor. b. Give a formula for S. c. Make a graph of S that shows the flushing process during the first 15 hours, and describe in words how the salt removal process progresses. d. In order to meet EPA standards, there can be no more than 3 pounds of salt in the tank. How long must the process continue before EPA standards are met? e. Suppose this cleanup procedure costs 8000 per hour to operate. How much does it cost to reduce the amount of salt from 60 pounds to 3 pounds? How much does it cost to reduce the amount of salt from 3 pounds to 0.1 pound?arrow_forward
- Functions and Change: A Modeling Approach to Coll...AlgebraISBN:9781337111348Author:Bruce Crauder, Benny Evans, Alan NoellPublisher:Cengage Learning