Last Updated on May 9, 2023
GMAT OFFICIAL GUIDE DS
Solution:
We are given that a taxi company charges f cents for the first mile of the taxi ride and m cents for each additional mile. We must determine how much the company charges for a 10-mile taxi ride. We can now set up the following equation:
Total Cost = f + m(total miles – 1)
Total Cost = f + m(10 – 1)
Total Cost = f + m(9)
Total Cost = f + 9m
Thus, if we determine the value of f and m, we can determine the total cost of a 10-mile taxi ride.
Statement One Alone:
The company charges $0.90 for a 2-mile ride.
We are given that the company charges 0.90 dollars for a 2-mile ride. Because we are already using cents in our equation we can convert 0.90 dollars to 90 cents.
90 = f + m(2 –1)
90 = f + m
Since we cannot determine the value of f and m, statement one alone is not sufficient to answer the question. We can eliminate answer choices A and D.
Statement Two Alone:
The company charges $1.20 for a 4-mile ride.
We are given that the company charges 1.20 dollars for a 4-mile ride. Because we are already using cents in our equation we can convert 1.20 dollars to 120 cents.
120 = f + m(4-1)
120 = f + 3m
Since we cannot determine the value of f and m, statement two alone is not sufficient to answer the question. We can eliminate answer choice B.
Statements One and Two Together:
From statements one and two we have the following two equations:
1) 90 = f + m
2) 120 = f + 3m
Since we have two independent equations with the same two variables, we have enough information to determine values for f and m, and thus we can determine how much a 10-mile taxi ride would cost.
