A taxi ride costs 0.25 per mile traveled. How much does a 5-mile taxi ride cost?
- A)
- B)
- C)
- D)
- E)
Answer
C
Key insight
The fare is a fixed 1.50 plus 0.25 for each of the 5 miles, so add 1.50 and 5 times 0.25.
Solution
The ride has two parts: a flat charge of that is paid regardless of distance, and a distance charge of for every mile.
Five miles cost dollars. Adding the flat charge:
The ride costs .
Why this works
A "fixed fee plus rate per unit" description is a linear function . Identify which number is the constant and which one gets multiplied by the quantity, then evaluate. This is the same structure as phone bills, rentals, and every other "base plus per-unit" word problem.
The trap
Adding the 0.25 only once (giving 1.75) instead of charging it for each of the 5 miles.
Common mistakes
- Adding the 0.25 only once (giving 1.75) instead of charging it for each of the 5 miles.
- Multiplying the flat fee by the number of miles () instead of the per-mile rate.
Techniques
Set up the equation/formula and compute; no special trick needed