A linear model fits a charge made of a fixed fee plus the same added amount for each unit. The phrase for each mile tells you which charge to multiply by the number of miles; the flat fee is added once. On a timed test, give each charge its job before matching a function. Adding the fees together first would treat both as per-mile charges.
Hints
- Hint 1
A rate is an amount charged for each unit. The words for each mile mean the mileage charge grows with the number of miles. What expression gives that charge for miles?
- Hint 2
A flat fee is paid once, regardless of how many miles you travel. Don't multiply it by along with the per-mile charge. How should you combine it with the mileage charge?
Step-by-step
Build the cost from its two charges
Step 1Find the mileage charge
No Desmos needed. The question gives charges in words to model, not an equation to evaluate or solve. The $2.00 for each mile is a rate, or dollars per mile. Since counts miles, multiply the rate by :
- Step 2
Add the flat fee once
The flat fee is paid once, so add $3.50 to the mileage charge:
Multiply the per-mile charge by ; add the flat fee once. This function gives the taxi's total cost in dollars for miles. Choice C.