Machine harvesting Corn - GMAT PREP CR

[RonPurewal]

In addition, when the required space is reduced from thirty inches to fifteen inches, the farmer should grow four times plants than before xD

^^ no.
there are twice as many rows, but the rows themselves are unchanged. so, twice as many plants.

[JbhB682]

Hi Experts -- reading the forum, it seems like option D is eliminated because

--- yield / plant has been reduced
--- option D says, number of plants has ALMOST doubled

Coupling both pieces together, the TOTAL out put of corn is certainly less than DOUBLE (and thus revenues are certainly less than DOUBLE)

But why are assuming that Revenues have to be DOUBLED ONLY in order to double profits (keeping costs the same)

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There are many instances where revenues have to be only increased by x 3/2 rather than x 2 in order to double profits (keeping costs the same obviously)

[JbhB682]

Hi Experts -- reading the forum, it seems like option D is eliminated because

--- yield / plant has been reduced
--- option D says, number of plants has ALMOST doubled

Coupling both pieces together, the TOTAL out put of corn is certainly less than DOUBLE

Given total output is less than double, profits cannot not be doubled

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The threshold that revenues HAVE TO BE DOUBLED in order to double profits (while keeping costs the same) -- I dont believe is accurate

There are many examples where revenues can be only increased by x 3/2 (not x 2) in order to double profits (keeping costs the same)

Example

10 $ in revenues - 5 $ in costs = 5 $ in profits

Increase revenues by x 3/2

15 $ in revenues - 5 $ in costs = 10 $ in profits

Profits have doubled by having revenues increase by x 3/2 only

Isn't this scenario (where total output has increased by x3/2 and not x2 but that is enough to double profits) a possibility with option D ?

[esledge]

The threshold that revenues HAVE TO BE DOUBLED in order to double profits (while keeping costs the same) -- I dont believe is accurate

There are many examples where revenues can be only increased by x 3/2 (not x 2) in order to double profits (keeping costs the same)

You are correct about this. A lot of the confusion in this thread comes from people conflating harvest “quantity” and “profit,” I think. All of the premises and choice (D) focus on corn yield per acre; (D) is especially tempting because of the neat math [1/(1/2) = 2] everyone (including me) wants to do. But the conclusion is about profit, which is not directly proportional to quantity, as you note.

profit = revenue – cost
profit = quantity*price – cost

In addition to your point about how cost can affect things, I’ll note that an alternative correct answer could have been written regarding the other independent variable: price. For example: “with the closer spacing of the rows, maximum kernel flavor can be achieved, and such corn sells for a premium price.”

[JbhB682]

But the conclusion is about profit, which is not directly proportional to quantity, as you note.

.”

Thank you Emily for responding.

I think this line above is where I am not able to wrap my head around (Given i am looking for an insight at the end of the day)

Profit = Quantity * Price - Cost
OR
Profit = [Yield/plant * Number of plant] * Price - Cost

Why only Increased prices (increased even by 1 $ ) or reduced cost (decreased even by 1 $) are directly proportional to increased profit.

Even an increased Quantity is technically directly proportional to increased profit.

Is the takeaway that perhaps
-- Optional D is not certain if Quantity is increased / same / decreased
whereas
-- option A and your proposed answer is CERTAIN that costs have gone down (Even if reduced by 1 $) / prices have gone up respectively (even if increased by 1 $)

It is the certainty (and it's implication on the profit -- even by 1 dollar ) which is the reason why option D is rejected whereas option A or your proposed solution are preferred

Thank you !

[esledge]

Even an increased Quantity is technically directly proportional to increased profit.

This is becoming more of a math discussion, but "x is directly proportional to y" means strictly that x = ky, where k is a constant. So really, none of the variables (Quantity, Price, Yield/plant, the number of plants, Cost) are directly proportional to Profit, because there's subtraction in the relationship, not just multiplication.

The CR take-aways are:

Why (D) is wrong:
(1) Don't be lured by the specificity of "the number of plants...will almost double" in (D)...This could be true and growers could NOT "double their profits," as your examples above show. Also, "almost double" falls short of "double," so this falls short of supporting the "double their profits" conclusion.
(2) Finally, (D) is a decent summary of the first two sentences in argument. It would be a good "Draw a Conclusion" answer if you were only given the first two sentences. Thus, it's not really new info, and it does not justify how "growers...double their profits."

Why (A) is right:
(1) "Minimize the need for costly" costs is not as specific as the language in (D), but it is more extreme in a good, supportive way. If costs are minimized (almost zero), that's ideal for Profit.
(2) By bringing up new info (costs), choice (A) adds to the given argument, strengthening the conclusion.

In short: you need a reason that you weren't already given. (A) provides that new reason, (D) just reiterates the given reasons.

[JbhB682]

Hi Emily - had an option D variant existed that said

option D variant)

with the spacing between rows cut by half, the number of plants grown per acre will almost TRIPLE

Would you still have selected Option A in that case ?

[esledge]

The GMAT would not make you choose between your revised D (with "triple" instead of "double") and existing choice A. There's no way for you to assess which of those strengthens the argument more (you'd need other numbers to be able to check).