1. The Argument Anatomy
Every logical plan is supported by two distinct pillars. Success in reasoning requires the ability to differentiate between static background data and the dynamic logical path.
The Situation (Static)
The background context, the identified problem, and the explicit goal. This is the "Landscape".
The Reasoning (Dynamic)
The specific logical path or "how" intended to connect the current situation to the desired outcome. This is the "Mechanism".
2. Level 1: The Growth Connection (Easy)
In this scenario, we examine a public health initiative. The plan's success hinges on a basic causal chain: Growth -> Substitution -> Nutrition.
"In parts of South America, vitamin-A deficiency is a serious health problem, especially among children. In one region, agriculturists are attempting to improve nutrition by encouraging farmers to plant a new variety of sweet potato called SPK004 that is rich in beta-carotene, which the body converts into vitamin A. The plan has good chances of success, since sweet potato is a staple of the region's diet and agriculture, and the varieties currently grown contain little beta-carotene"
Which of the following, if true, most strongly supports the prediction that the plan will succeed?
- (A) The growing conditions required by the varieties of sweet potato currently cultivated in the region are conditions in which SPK004 can flourish.
- (B) The flesh of SPK004 differs from that of the currently cultivated sweet potatoes in color and texture...
- (C) There are no other varieties of sweet potato that are significantly richer in beta-carotene than SPK004 is.
- (D) The varieties of sweet potato currently cultivated in the region contain some important nutrients that are lacking in SPK004.
- (E) There are other vegetables currently grown in the region that contain more beta-carotene than the currently cultivated varieties of sweet potato do.
Solution Walkthrough: The Sweet Potato
Goal: Improve nutrition via SPK004.
Step 1The Logic Bridge
Step A (Growth): SPK004 must grow effectively.
Step B (Substitution): People must eat it.
Goal: Better Health.
Step 2The Support (Option A)
(A) The growing conditions... are conditions in which SPK004 can flourish.
This confirms Step A. If it couldn't grow there, the plan would fail immediately. Knowing it flourishes supports the plan.
Step 3The Failure Point (Option B)
(B) says the texture/color is different. This might make people NOT eat it (Failure of Step B). This would weaken the plan.
3. Level 2: The Precision Gap (Medium)
This case introduces technical variables. The plan relies on a machine's ability to distinguish between targets based on a specific attribute (Color).
"A company plans to develop a prototype weeding machine that uses cutting blades with optical sensors and microprocessors that distinguish weeds from crop plants by differences in shade of color. The inventor of the machine claims that it will reduce labor costs by virtually eliminating the need for manual weeding"
Which of the following is a consideration in favor of the company's implementing its plan to develop the prototype?
- (A) There is a considerable degree of variation in shade of color between weeds of different species.
- (B) The shade of color of some plants tends to change appreciably over the course of their growing season.
- (C) When crops are weeded manually, overall size and leaf shape are taken into account in distinguishing crop plants from weeds.
- (D) Selection and genetic manipulation allow plants of virtually any species to be economically bred to have a distinctive shade of color without altering their other characteristics.
- (E) Farm laborers who are responsible for the manual weeding of crops carry out other agricultural duties at times in the growing season when extensive weeding is not necessary.
Solution Walkthrough: The Weeding Machine
Mechanism: Distinguish by COLOR shade.
Step 1The Success Path
The machine only works if the color difference is reliable. If colors are too similar or variable, the sensors fail.
Step 2The Standardization (Option D)
(D) Selection... allow plants... to be bred to have a distinctive shade of color.
This allows us to force the environment to match the machine. By making crops a unique color, we guarantee the sensors work. Correct Support.
Step 3The Logic Gap (Option A)
(A) says weeds have 'considerable variation' in color. This is bad! If weeds are many different colors, it's harder for the machine to distinguish them from crops. This weakens the plan.
4. Level 3: The Profitability Trap (Hard)
At the highest level, you must distinguish between what affects the Outcome (Profit) and what is merely background information.
"Tanco, a leather manufacturer, uses large quantities of common salt to preserve animal hides. New environmental regulations have significantly increased the cost of disposing of salt water that results from this use, and, in consequence, Tanco is considering a plan to use potassium chloride in place of common salt. Research has shown that Tanco could reprocess the by-product of potassium chloride use to yield a crop fertilizer, leaving a relatively small volume of waste for disposal."
In determining the impact on company profits of using potassium chloride in place of common salt, it would be important for Tanco to research all of the following EXCEPT:
- (A) What difference, if any, is there between the cost of the common salt needed to preserve a given quantity of animal hides and the cost of the potassium chloride needed to preserve the same quantity of hides?
- (B) To what extent is the equipment involved in preserving animal hides using common salt suitable for preserving animal hides using potassium chloride?
- (C) What environmental regulations, if any, constrain the disposal of the waste generated in reprocessing the by-product of potassium chloride?
- (D) How closely does leather that results when common salt is used to preserve hides resemble that which results when potassium chloride is used?
- (E) Are the chemical properties that make potassium chloride an effective means for preserving animal hides the same as those that make common salt an effective means for doing so?
Solution Walkthrough: The Leather Switch
Goal: Determine Profitability. Find the IRRELEVANT factor.
Step 1Filter for Profit Drivers
- (A) Cost of materials? Relevant.
- (B) Equipment cost? Relevant.
- (C) Disposal cost? Relevant.
- (D) Product quality (Sales)? Relevant.
Step 2The Irrelevant Detail (Option E)
(E) Are the chemical properties... the same?
The passage already implies that potassium chloride IS an effective preservative. Why or How it works chemically doesn't change the cost. We just need to know IF it works (which is given), not HOW.
Step 3Conclusion
Option E is scientific background info, not a business variable. It is the correct answer (the Exception).
Summary: The 4-Step Checklist
- Isolate the Goal: Improve health? Reduce labor? Maximize profit?
- Identify the Bridge: What mechanism connects the plan to the goal?
- Identify Sensitivities: If this variable changes (e.g. color variance), does the plan break?
- Filter Irrelevancies: Ignore factors that don't impact the core bridge.
