X and Y, two computer engineers, built identical websites at different constant rates. X, working alone for 7 hours, built some of the website; then Y, working alone for 6 hours, built the rest of the website. How many hours would it have taken X, working alone, to build all of the website?
1. X built one part 15 minutes
2. X built four times as many parts in 7 hours as Y built in 6 hours
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Answer
Statement 2 provides us with an equation relating the two rates: 7X = 4(6Y).
We can simplify this formula to get one rate in terms of the other. The first step is to calculate the expression on the right-hand side: 7X = 24Y.
Now divide both sides by 24: 7/24 X=Y.
Statement 2 is sufficient on its own.
Correct Answer B