Concept explainers
African Elephant Populations
Although millions of elephants once roamed across Africa, by the mid-1980s elephant populations in African nations had been devastated by poaching. Elephants are important to African ecosystems. In tropical forests, elephants create clearings in the canopy that encourage new tree growth. In savannas, elephants reduce bush cover to create an environment that is favorable to browsing and grazing animals. In addition, the seeds of many plant species depend on passing through an elephant’s digestive tract before germination.
The status of the elephant now varies greatly across the continent; in some nations, strong measures have been taken to effectively protect elephant populations, while in other nations the elephant populations remain in danger due to poaching for meat and ivory, loss of habitat, and conflict with humans. Table 3.13 shows elephant populations for several African nations in 1979, 1989, and 2007 (Lemieux and Clarke, “The International Ban on Ivory Sales and Its Effects on Elephant Poaching in Africa,” British Journal of Criminology, 49(4), 2009).
The David Sheldrick Wildlife Trust was established in 1977 to honor the memory of naturalist David Leslie William Sheldrick who founded Warden of Tsavo East National Park in Kenya and headed the Planning Unit of the Wildlife Conservation and Management Department in that country. Management of the Sheldrick Trust would like to know what these data indicate about elephant populations in various African countries since 1979.
Managerial Report
Use methods of
- 1. The mean annual change in elephant population for each country in the 10 years from 1979 to 1989, and a discussion of which countries saw the largest changes in elephant population over this 10-year period.
- 2. The mean annual change in elephant population for each country from 1989 to 2007, and a discussion of which countries saw the largest changes in elephant population over this 18-year period.
- 3. A comparison of your results from parts 1 and 2, and a discussion of the conclusions you can draw from this comparison.
Want to see the full answer?
Check out a sample textbook solutionChapter 3 Solutions
EBK STATISTICS FOR BUSINESS & ECONOMICS
- Suppose the coal and steel industries form a closed economy. Every $1 produced by the coal industry requires $0.30 of coal and $0.70 of steel. Every $1 produced by steel requires $0.80 of coal and $0.20 of steel. Find the annual production (output) of coal and steel if the total annual production is $20 million.arrow_forwardCholesterol Cholesterol in human blood is necessary, but too much can lead to health problems. There are three main types of cholesterol: HDL (high-density lipoproteins), LDL (low-density lipoproteins), and VLDL (very low-density lipoproteins). HDL is considered “good” cholesterol; LDL and VLDL are considered “bad” cholesterol. A standard fasting cholesterol blood test measures total cholesterol, HDL cholesterol, and triglycerides. These numbers are used to estimate LDL and VLDL, which are difficult to measure directly. Your doctor recommends that your combined LDL/VLDL cholesterol level be less than 130 milligrams per deciliter, your HDL cholesterol level be at least 60 milligrams per deciliter, and your total cholesterol level be no more than 200 milligrams per deciliter. (a) Write a system of linear inequalities for the recommended cholesterol levels. Let x represent the HDL cholesterol level, and let y represent the combined LDL VLDL cholesterol level. (b) Graph the system of inequalities from part (a). Label any vertices of the solution region. (c) Is the following set of cholesterol levels within the recommendations? Explain. LDL/VLDL: 120 milligrams per deciliter HDL: 90 milligrams per deciliter Total: 210 milligrams per deciliter (d) Give an example of cholesterol levels in which the LDL/VLDL cholesterol level is too high but the HDL cholesterol level is acceptable. (e) Another recommendation is that the ratio of total cholesterol to HDL cholesterol be less than 4 (that is, less than 4 to 1). Identify a point in the solution region from part (b) that meets this recommendation, and explain why it meets the recommendation.arrow_forwardWhat operations can be performed on a linear system to arrive at an equivalent system?arrow_forward
- The Ancient Murrelet is a plucky little bird of the auk family that lives in colonies on islands off the northern Pacific coasts of Russia, Alaska and Canada. Half of the world population breeds on the islands of Haida Gwaii, British Columbia. Since these birds lay their eggs in burrows on the forest floor, the nestlings are highly susceptible to predation. Their populations have been greatly reduced over the past century by mammalian predators (deer, raccoons, rats) introduced to their breeding islands after contact was established between the Haida people and outsiders. Conservation efforts have only recently been undertaken. A multi-year population study on one island, now closed to human visitors, has produced the following function that describes the observable decline: P(t) = 5-√√2t+4 where P(t) is the island population in thousands and t is the time in years since January 1, 2008, when the study was started. The goal is to graph and interpret this function in this problem…arrow_forwardA forest consists of two types of trees; those that are 0-5 ft and those that are taller than 5 ft. Each year, 40% of all 0-5 ft trees die. 10% are sold for $20 each. 30% stay between 0-5 ft and 20% grow more than 5 ft. Each year 50% of all trees taller than 5 ft are sold for $50, 20% are sold for $30 and 30% remain in the forest. A. What is the probability that a 0-5 ft tall tree will die before being sold and if a tree less than 5 ft is planted what is the expected revenue earned from that tree. (not solved with excel please)arrow_forwardIKEA has a contract to deliver 100, 250, 190, 140, 220, and 110 home windows over the next 6 months. Production cost (labor, material, and utilities) per window varies by period and is estimated to be $50, $45, $55, $48, $52, and $50 over the next 6 months. To take advantage of the fluctuations in manufacturing cost, IKEA can produce more windows than needed in a given month and hold the extra units for delivery in later months. This will incur a storage cost at the rate of $8 per window per month, assessed on the end-of season inventory. Now IKEA wants to minimize their respective cost. Based on this data answer the following questions Qus.1)Write down the objective function of the linear programming consistent with the objective of IKEA.arrow_forward
- The water-supply manager for a Midwest city needs to supply the city with at least 10 million gal of potable (drinkable) water per day. The supply may be drawn from the local reservoir or from a pipeline to an adjacent town. The local reservoir has a maximum daily yield of 6 million gallons of potable water, and the pipeline has a maximum daily yield of 10 million gallons. By contract, the pipeline is required to supply a minimum of 6 million gallons/day. If the cost for 1 million gallons of reservoir water is $300 and that for pipeline water is $600, how much water should the manager get from each source to minimize daily water costs, C, for the city?arrow_forwardThe amount of nitrogen (in lb/acre), phosphate (in lb/acre), and labor (in hr/acre) needed to grow honeydews, yellow onjons, and lettuce is given by the table to the right. Complete parts a and b. OA. Yes, the farmer should allot B. No, it is not possible to use all resources completely. acres for honeydew, for yellow onions, and acres for lettuce. Honeydews 120 Nitrogen Phosphate 180 Labor 5 a) If the farmer has 230 acres, 30,300 lb of nitrogen, 34,400 lb of phosphate, and 400 hours of labor, is it possible to use all resources completely? If so, how many acres should he allot for each crop? Select the correct choice below and, if necessary, fill in the answer box to complete your choice. ⒸA. Yes, the farmer should allot acres for honeydew, OB. No, it is not possible to use all resources completely. Yellow onions 150 acres for lettuce. 80 6 Lettuce b) Suppose everything is the same as in part a, except that 1180 hours of labor are available. Is it possible to use all resources…arrow_forwardFarm Fact #3: In 2007, Massachusetts maple producers set 230,000 taps to collect sap, which, after boiling produced 30,000 gallons of maple syrup. It takes about 40 gallons of sap to produce one gallon of syrup." And "Suppose the sap is collected in gallon buckets that hang under each tap, and the maple season lasts one month? And "Read the label of a "pancake syrup" bottle to find out how much maple syru it contains." How many gallons of syrup did each tap yleld? How many gallons of sap did each tap yield? What extra information would you need ot estimate the number of sugar maple trees that were tapped? How many times a day (how often) will the buckets of sap need to be emptled? (What fraction of a bottle of generic "pancake syrup" is pure maple syrup?) What fraction of the cost of generic "pancake syrup" can you attribute to the cost of pure maple syrup?arrow_forward
- A freshly brewed shot of espresso has three distinct components: the heart, body, and crema. The separation of these three components typically lasts only 10 to 20 seconds. To use the espresso shot in making a latte, a cappuccino, or another drink, the shot must be poured into the beverage during the separation of the heart, body, and crema. If the shot is used after the separation occurs, the drink becomes excessively bitter and acidic, ruining the final drink. Thus, a longer separation time allows the drink-maker more time to pour the shot and ensure that the beverage will meet expectations. An employee at a coffee shop hypothesized that the harder the espresso grounds were tamped down into the portafilter before brewing, the longer the separation time would be. An experiment using 24 observations was conducted to test this relationship. The independent variable Tamp measures the distance, in inches, between the espresso grounds and the top of the portafilter (i.e., the harder the…arrow_forwardA freshly brewed shot of espresso has three distinct components: the heart, body, and crema. The separation of these three components typically lasts only 10 to 20 seconds. To use the espresso shot in making a latte, a cappuccino, or another drink, the shot must be poured into the beverage during the separation of the heart, body, and crema. If the shot is used after the separation occurs, the drink becomes excessively bitter and acidic, ruining the final drink. Thus, a longer separation time allows the drink-maker more time to pour the shot and ensure that the beverage will meet expectations. An employee at a coffee shop hypothesized that the harder the espresso grounds were tamped down into the portafilter before brewing, the longer the separation time would be. An experiment using 24 observations was conducted to test this relationship. The independent variable Tamp measures the distance, in inches, between the espresso grounds and the top of the portafilter (i.e., the harder the…arrow_forwardhe Swamp Palace Museum (SPM) is an interactive museum that teaches visitors the ways of life on the swamps of the southern United States. Visitors can visit over 100 exhibits demonstrating the ecology of the swamp and the habits of the animals and insects that call the swamp home. Additionally, the museum includes several fast-food and full service restaurants and opportunity for swimming and several thrill rides. The park was originally supported with one time government funding but now it has to become self-supporting. After five years of operation, the park has not lacked for visitors but has struggled just to break-even. The Swamp Palace has sought help from the Marketivity Group to help them address the long-term viability of the park. Several technologies are considered as ways of enhancing value. One is a mobile phone app that will provide oral and visual navigation aids around the park. For instance, if someone says “take me to the Blind Bayou Bar,” the phone will give…arrow_forward
- Linear Algebra: A Modern IntroductionAlgebraISBN:9781285463247Author:David PoolePublisher:Cengage LearningAlgebra for College StudentsAlgebraISBN:9781285195780Author:Jerome E. Kaufmann, Karen L. SchwittersPublisher:Cengage Learning
- Algebra and Trigonometry (MindTap Course List)AlgebraISBN:9781305071742Author:James Stewart, Lothar Redlin, Saleem WatsonPublisher:Cengage LearningCollege AlgebraAlgebraISBN:9781305115545Author:James Stewart, Lothar Redlin, Saleem WatsonPublisher:Cengage Learning