# Word problems and equations

1.The equation C=mx+b can be used to model the monthly cost, C, of a cell phone plan where b is the flat monthly cost, m represents the cost in dollars per minute and x is the number of minutes used in the month. Choose a flat monthly rate and cost per minute and insert the values you have chosen for m and b into the equation. Then use this equation to find the total monthly cost, C, if 68 minutes are used.

2.The equation A=(LP)/2-L^2, gives the area of a rectangle of perimeter P and length L. Suppose that you have 600 feet of fencing which you plan to use to fence in a rectangular area of land. Choose any two lengths for a rectangle and find the corresponding area for each using the given equation. Include units and show all calculations. Which of the two lengths that you chose gives a larger area? What is the corresponding width of each of the two rectangles?

3.Using the Library, web resources, and/or other materials, find the gas mileage of your dream car or any car of your choice. Let x be the number of miles driven on 50 gallons of gas. By setting up and solving a proportion involving x, find the value of x for the car that you have chosen. State the type of car, the mileage, and show both the set up of the proportion and the steps to solve. Include units with your answer.

4.The equation D=sqrt(1.30h), can be used to approximate the distance, D, in nautical miles that a person can see to the horizon from a height, h, in feet. This equation includes a correction for the refraction of light. Suppose that you are in an airplane. By choosing any height, find the corresponding distance that you should be able to see to the horizon. Include the height and the calculations needed to find the distance. Include units with your answer, and show all work for full credit.

5.Using the Library, web resources, and/or other materials, find the most recent report of the annual inflation rate of a country of your choice as well as the type of currency used in that country. The equation S=C(1+r/100)^5 to find the inflated cost S, in 5 years, of an item, good or service, where C is the current price of that item in that country's currency and where the inflation rate is r%. Choose any value of C, the current price of an item in that country's currency, that you would like.

Include in your post the country, the inflation rate, the type of currency, a value of C of your choice, and the calculations needed to find the approximated inflated rate of C after 5 years.

#### Solution Summary

This provides several examples of working with equations and word problems, including distance, inflation, mileage, perimeter, and cost.