Concept explainers
Reminder Round all answers to two decimal places unless otherwise indicated.
An Expensive Book A scientist visited Amazon.com to purchase a book. To his amazement, he found the book priced at
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Functions and Change: A Modeling Approach to College Algebra (MindTap Course List)
- Heart 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_forwardClearance A department store is clearing out merchandise in order to make room for new inventory. The plan is to mark down items by 30% each week. This means that each week the cost of an item is 70% of the previous week’s cost. If the original cost of a sofa was $1,000, the cost for the first week would be $1000(0.70) and the cost of the item during the second week would be $1,000(0.70)2. Complete the table shown below. What will be the cost of the sofa during the fifth week? Simplify the expression, to show the cost in dollars.arrow_forwardMortgage 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_forward
- An earthquake in Mexico in 1985 had and intensity level about 125, 000, 000 times the reference intensity. Find the Richter number for that earthquake.arrow_forwardCell Phone Plans Gwendolyn is mulling over the three cell phone plans shown in the table. Gigabytes GB of data included Monthly Cost Each additional megabytes MB Plan A Plan B Plan C 1 1 1 25.00 40.00 60.00 2.00 1.50 1.00 From past experience, Gwendolyn knows that she will always use more than 1GB of cell phone data every month. aMake table of values that shows the cost of each plan for 1 GB to 4 GB, in 500 MB increments. bFind formulas that give Gwendolyns monthly cost for each plan, assuming that she uses x gigabytes of data per month where x1. cWhat is the charge from each plan when Gwendolyn uses 2.2 GB? 3.7 GB? 4.9 GB? d Use your formulas from part b to determine the number of gigabytes of data usage for which: (i) Plan A and Plan B give the same cost. (ii) Plan A and Plan C give the same cost. (iii) Plan B and Plan C give the same cost.arrow_forwardRound 0.42538 to 2 decimal places.arrow_forward
- Estimate the age of a newly discovered fossil for which the ratio of carbon-14 to carbon-12 is R=1/1014.arrow_forwardIn 2014, Chile experienced an intense earthquake with a magnitude of 8.2 on the Richter scale. In 2014, Los Angeles also experienced an earthquake which measured 5.1 on the Richter scale. Compare the intensities of the two earthquakes.arrow_forwardThe astronauts of Expedition 28 on the International Space Station spend 15 weeks in space. Convert the time to minutes.arrow_forward
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