Exercise Answers
Discrete Quantitative Questions
- D
Step 1: Choose a smart value for x: Let x = 3.
Step 2: Substitute 3 for x in the question and determine the “goal”:
The cost of the first minute = $0.75. The cost for the next two minutes =
$0.50(2) = $1. The total cost = $1.75. Goal: $1.75
Step 3: Substitute 3 for x in the choices, and identify which choice yields a
value that matches your goal: $1.75
The only choice that yields a value of $1.75 is D. - C
Step 1: Choose smart values: Let x = 5 and y = 15. Substitute these values to
determine a value for z: 2(5) + 3(15) = 60. Thus when x = 5 and y = 15,
z = 60.
Step 2: Substitute 5 for x in the question and determine the “goal”: In this
case, you want to solve for x, so the goal is simply the value that you chose
for x: 5.
Step 3: Substitute 15 for y and 60 for z in the choices, and identify which
choice yields a value that matches your goal: 5. The only choice that yields a
value of 5 is C. - C
Step 1: Choose smart values for x and y: Let x = 10 and y = 5.
Step 2: Substitute 10 for x and 5 for y in the question and determine the
“goal.” Since you want half the distance to the school, let’s use these values
to get the entire distance, and then divide by 2. In this case, the total
distance to the school is (miles/hour) x # of hours = xy = 10 × 5 = 50. Half
of the distance is thus 50/2 = 25. The goal is 25.
Step 3: Substitute 10 for x and 5 for y in the choices, and identify which
choice yields a value that matches your goal: 25. The only choice that yields
a value of 25 is C. - D
Step 1: Choose smart values: Let a = 5 and b = 20.
Step 2: Substitute 5 for a and 20 for b in the question and determine the
goal: If 5 shirts cost $20, then each shirt is $20/5 = $4. The cost of six shirts
will thus be 6 × $4 = 24. The goal is 24.
Step 3: Substitute 5 for a and 20 for b in the choices, and identify which
choice yields a value that matches your goal: 24. The only choice that yields
a value of 24 is D. - C Since the distance for both trips is the same, the answer should provide a
value of x that yields the same distance for both trips. You can determine the
CHAPTER 7 ■ TWO ESSENTIAL QUANTITATIVE REASONING STRATEGIES 15702-GRE-Test-2018_107-172.indd 157 13/05/17 11:06 am