- B Let b = Bob’s weight and s = Sara’s weight. If Bob is currently 30 pounds
heavier than Sara, then b = s + 30. If they each gain 30 pounds, then Bob’s
new weight will be b + 30 and Sara’s new weight will be s + 30. After these
changes, Bob’s weight will be 25% more than Sara’s. We can translate this as:
b + 30 = 1.25(s + 30). To solve for b, we should use the first equation to express
s in terms of b: b = s + 30 → b − 30 = s. Substitute (b − 30) for s in the second
equation and solve for b:
b + 30 = 1.25(b − 30 + 30) → b + 30 = 1.25 b → 30 = .25b → b = 120. - E Use the given constraints to determine whether each choice could equal zero.
A: If x = 0, then xy = 0. Eliminate A.
B: If x = 3, and y = −3, then x + y = 0. Eliminate B.
C: If x = 3, and y = 3, then x − y = 0, Eliminate C.
D: Factor: xy − y^2 = y(x − y). For y(x − y) to be zero, either y must be zero or
x − y must be 0; y cannot be 0, but x − y = 0 if x = y. Eliminate D.
E: When a value is raised to an even exponent, the result must be greater
than or equal to zero. Thus, y^2 > 0, and x^2 ≥ 0. The sum of y^2 and x^2 is thus
greater than 0. - C The base of both triangles has a length of 8. The height of triangle ADC is 7.
The area of triangle ABC is thus (^12 ) × 8 × 7 = 28. The height of triangle ABC is
14. The area of triangle ABC is thus (^12 ) × 8 × 14 = 56
574 PART 5 ■ GRE PRACTICE TESTS05-GRE-Test-2018_463-582.indd 574 12/05/17 12:14 pm