Part II – Gas Guzzler
Cody’s parents decided to keep the SUV and trade in their Corolla for the Hybrid. They also decided to let Cody drive the SUV. “Happy Birthday, Son,” said Mr. Andrews. “Here are the keys. Be careful!”
“Wow, thanks, Dad!” Cody took the keys and ran outside. The SUV was shining in the evening sunset light. He couldn’t wait to take it for a spin around the block.
After a week of driving, Cody quickly realized that he got stuck with the gas guzzler. He wasn’t making that much money at his crummy minimum wage job. He was starting to think that he might need to get a second job just to buy gas!
“Dad,” Cody said, “I had no idea the SUV used so much gas. I’m only driving to work and school, but it’s costing me a fortune.”
“Don’t worry,” said Mr. Andrews. “Your mother and I will give you the money that we’re saving on gas with our Hybrid to help fill up your tank.”
Questions
Let’s take our four cars and say we drive them for 100 miles. Now answer the following questions.
First, calculate the number of gallons needed to drive 100 miles in each car and place this value in the fourth column of Table 1. Then, project the cost if the gasoline is priced at $4 per gallon and place these costs in the last column. Note: Round all answers to the hundredths.
Table 1 Car Distance (miles) Miles per gallon (mpg) Gallons of gas needed to go 100 miles Cost ($) to go 100 miles if gas costs $4 per gallon SUV 100 13 Minivan 100 17 Corolla 100 28 Hybrid 100 48 Assuming that Cody’s family needs one small car (Corolla or Hybrid) and one large car (SUV or Minivan), calculate the total cost of each combination possible in the table below.
Table 2 Car combination Total cost (in $) to drive each car 100 miles SUV-Corolla Minivan-Corolla SUV-Hybrid Minivan-Hybrid Which combination would be the most expensive for the family?
Which combination would be the most economical for the family?
As noted in Part I, Cody’s parents currently have a Corolla and an SUV. What is the total cost (in $) to drive 100 miles in the vehicles that Cody’s parents started with?
Also, as discussed in Part I, Cody’s parents are planning to trade only one car. They can keep the Corolla and trade the SUV for a Minivan or they can keep the SUV and trade the Corolla for the Hybrid. Fill in Table 3 to help you decide which trade would save Cody’s family the most money from what they have now.
Table 3 Cost to drive 100 miles with the vehicles that Cody’s parents have before the trade Cost to drive 100 miles in the new combination of cars after the trade Savings in dollars (difference between column A and B) SUV & Corolla = $ Minivan & Corolla = $ SUV & Corolla = $ SUV & Hybrid = $
Go back to Part I and look at the hypothesis you constructed in Question 1. You were asked to formulate a hypothesis based on which vehicle Cody’s parents should keep and which vehicle they should trade in terms of saving the most money on gasoline.
Do the calculations in Table 3 prove or disprove your hypothesis? Reflect about this and offer an explanation.
Cody’s parents chose to keep the SUV and trade in the Corolla for the Hybrid. Did they make the right decision in terms of saving money? Explain.
Cody’s father, Mr. Andrews, offered to help Cody pay for gas for the SUV: “Don’t worry,” said Mr. Andrews. “Your mother and I will give you the money that we’re saving on gas with our Hybrid to help fill up your tank.” Calculate how many gallons of gasoline Cody’s parents were able to buy for Cody, assuming that gas is priced at $4 per gallon and the cars are driven 100 miles.
How many miles would this amount of gasoline get Cody with the SUV making 13 mpg?
Originally published at http://www.sciencecases.org/gas_mileage/case2.asp
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