False chicory's taproot is always one half as long as the plant is tal

Question

False chicory's taproot is always one half as long as the plant is tall. Furthermore, the more rain false chicory receives, the taller it tends to grow. In fact, false chicory plants that receive greater than twice the average rainfall of the species' usual habitat always reach above-average heights for false chicory.

If the statements above are true, then which one of the following must also be true?

(A) If two false chicory plants differ in height, then it is likely that the one with the shorter taproot has received less than twice the average rainfall of the species' usual habitat.

(B) If a false chicory plant has a longer-than average taproot, then it is likely to have received more than twice the average rainfall of the species' usual habitat.

(C) It is not possible for a false chicory plant to receive only the average amount of rainfall of the species' usual habitat and be of above average height.

(D) If the plants in one group of false chicory are not taller than those in another group of false chicory, then the two groups must have received the same amount of rainfall.

(E) If a false chicory plant receives greater than twice the average rainfall of the species' usual habitat, then it will have a longer taproot than that of an average-sized false chicory plant.

tuanquang269 · Accepted Answer

The argument that contains many words makes the question become harder to solve. To make the argument easier. I will define the "False chicory plan" = X

=> Argument Evaluation: X's taproot = 1/2 X
Furthermore, the more rain X get, the taller X is
In fact, X that receives >2 average rainfall of usual reception is higher than the average height of X

(A) If two false chicory plants differ in height, then it is likely that the one with the shorter taproot has received less than twice the average rainfall of the species' usual habitat.  => If 2 X differ in height, then it is likely that the X1 (shorter taproot) has received less than 2 average rainfall of X
=> These matter are not mentioned in the argument. 
(B) If a false chicory plant has a longer-than average taproot, then it is likely to have received more than twice the average rainfall
of the species' usual habitat. => If X's taproot is longer than X's average taproot, then it is likely to have received more than twice the average rainfall => This was stated in the argument. If you choose this choice as the correct answer. It's a trap. This answer is the reverse form of the argument. 
(C) It is not possible for a false chicory plant to receive only the average amount of rainfall of the species' usual habitat and be of above
average height.  => not mentioned 
(D) If the plants in one group of false chicory are not taller than those in another group of false chicory, then the two groups must have
received the same amount of rainfall.  => not mentioned 
(E) If a false chicory plant receives greater than twice the average rainfall of the species' usual habitat, then it will have a longer taproot than
that of an average-sized false chicory plant.  => If X receive >2 rainfall of the average X, then X will have longer than average (+ height of taproot = exactly 1/2 height of X) => the X'taproot will be higher than the average that of average X

GMATNinjaTwo · Answer

Let's take a look at option B...

We know that "False chicory's taproot is always one half as long as the plant is tall.", so if a false chicory plant has a longer-than average taproot, then it is also taller than average. We know that "false chicory plants that receive greater than twice the average rainfall of the species' usual habitat always reach above-average heights", BUT we do not know that the  reverse  is true; in other words, we do not know that false chicory plants that reach above-average heights always (or even mostly) receive greater than twice the average rainfall of the species' usual habitat.

If that is unclear, imagine there are 100 false chicory plants, and 30 of those plants receive greater than twice the average rainfall of the species' usual habitat. According to the statements in the passage, those 30 plants MUST reach above-average heights. But that same group of 100 plants might include 50 plants that reach above-average heights even though they do NOT receive greater than twice the average rainfall of the species' usual habitat. Thus, statement B is not necessarily true.

GMATNinja · Answer

To repeat our  public service announcement : chatgpt isn't very good at the GMAT. More broadly, it's a bad idea try to invent some "formula" for what you are or aren't going to pick before reading the answer choices.

Instead, you'll want to think hard about each one and ask yourself, "If everything in the passage is true, does this choice have to be true as well?" So let's do that.

This one is pretty easy to rule out with an example.

Let's say we have two false chicory plants that each received   greater than twice   the average rainfall of the usual habitat. One of those two received   three times   the average rainfall and the other received   ten times   the average rainfall. All else equal, we'd expect the one that received ten times the average rainfall to be taller than the other one ("the more rain false chicory receives, the taller it tends to grow").

So it's very plausible to have two plants that differ in height even though NEITHER received less than twice the average rainfall of the species' usual habitat. This goes against (A), so (A) can be eliminated.

Again, we can use an example. Let's say that a false chicory plant received 1.5 times the average rainfall of the usual habitat. All else equal, we'd expect this plant to be taller than average ("the more rain false chicory receives, the taller it tends to grow") and thus have a longer-than average taproot., even though is has NOT received more than twice the average rainfall.

Also keep in mind that rainfall is just one factor, and there could certainly be other factors affecting height. So false chicory plants could potentially reach above-average heights (and thus have longer-than average taproots) even though they only receive average -- or perhaps even BELOW average -- rainfall amounts.

Again, "the more rain false chicory receives, the taller it   tends   to grow," but that doesn't rule out the possibility of exceptions to that trend. (That's what Chat GPT was trying to explain with it's dramatic "illegal reversal" stuff.)

(B) is out.

The second half of the explanation for choice (B) also applies here: "the more rain false chicory receives, the taller it   tends   to grow," but that doesn't rule out the possibility of exceptions to that trend. There could certainly be other factors affecting height, so it's very possible to have a false chicory plant that has an above-average height even though it receives the average amount of rainfall. (C) is out.

As explained for both (B) and (C), other factors could affect height. So it's possible for the two groups to have the same height even though one group received more rainfall. For example, maybe the group that received less rainfall was exposed to more sunlight, and more sunlight means more height. (D) is out.

We know from the passage that "false chicory plants that receive greater than twice the average rainfall of the species' usual habitat   always   reach above-average heights for false chicory." So a plant consistent with choice (E) MUST have an above-average height.

We also know that "false chicory's taproot is   always   one half as long as the plant is tall." So a plant with an above-average height MUST have an above-average taproot. So (E) must be true.

I hope that helps!

Archit143 · Answer

I think the answer must be E and not A ...The argument uses the strong wording in the last sentence ie "ALWAYS" the the plant will grow twice the avg height, when condition of rainfall is met.
But in A the uses of word "Likely" disqualifies it to be the answer.

Consider Kudos If my post helps!!!!!!!!!!!!

Archit

anje29 · Answer

Correct answer is E. More discussion here https://www.manhattanprep.com/lsat/foru ... t5097.html

abhimahna · Answer

Hi,

Can someone please help me understand why option B is incorrect here?

I think option E is too unlikely to mark as the correct answer. The whole question deals with likelihood and in E we have MUST. I would always prefer to avoid such extreme options. Please suggest.

Thanks

abhimahna · Answer

Thank you  GMATNinjaTwo .

So, in that case should we consider E, even though it is too extreme/broad to consider? (It has MUST-- which makes me a bit dicey)

GMATNinjaTwo · Answer

abhimahna ,

Let's take a look at choice E...

We know that "false chicory plants that receive greater than twice the average rainfall of the species' usual habitat ALWAYS reach above-average heights". So if a false chicory plant receives greater than twice the average rainfall of the species' usual habitat, then the plant WILL reach above-average heights; if the plant reaches above-average heights, the length of its taproot WILL also be above average (since "false chicory's taproot is ALWAYS one half as long as the plant is tall."). Thus, even though choice E sounds "extreme", it is supported by the statements in the passage.

DharLog · Answer

Traps-traps.
Only E gives undoubtful statement

Namangupta1997 · Answer

Can anyone explain why is C incorrect ?

unraveled · Answer

Taproot is ALWAYS half of height. Those that receive greater than twice the average rainfall of the species' usual habitat ALWAYS reach above-average heights for false chicory. 
Can you say that 100% reverse is true for second sentence above.??

C says it is not at all possible for a plant to be of above average height after receiving average amount of rainfall. There are two sets of plant here:
1. One that ALWAYS reach above average height after receiving more than twice of average rainfall.
2. One that MAY or MAY NOT reach above average height after receiving average rainfall.

Second point has two subsets of plants.

HTHs.

Rickooreoisb · Answer

GMATNinja - Can you please share your thoughts on this question and each of the options. Also is it right to say that this question says A casues B. So let's reject option with framing if B is there then A happened ? and hence we should reject option A and B? This is the reasoning given by chatgpt which I dont agreement with

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egmat · Answer

The Passage Gives Us: 
 
 Taproot = 1⁄2 × Height ( ALWAYS  - bidirectional) 
 More rain → taller ( TENDS  - not guaranteed)

Why (A) Fails - Unsupported "Likely":  
Option A says the shorter plant  likely  received <2x rainfall.
 Problem:  The "shorter" plant between two could still be above-average in absolute terms!
Example:
 
 Plant 1:  150%  of average height 
 Plant 2:  120%  of average height  
Plant 2 is "shorter" but still above average - could have received >2x rainfall.
We have  no probability data  to claim what's "likely."

Why (B) Fails - Illegal Reversal: 
  Passage says: >2x rainfall → above-average height
Option B claims: above-average height → >2x rainfall
 This reverses the logic! 
Think of it this way: "All dogs are mammals" ≠ "All mammals are dogs"
A plant could be above-average height from receiving  1.5x  rainfall. We only know >2x  guarantees  tallness, not that it's the  only  cause.

Why (C) Fails - "Not Possible" is Too Strong: 
 Option C claims: Average rainfall →  impossible  to be above-average height

Problem:  The passage never says this!
We're told:

We're  NOT  told >2x rainfall is  required  for above-average height (not a necessary condition)

A plant could be above-average height with just average rainfall due to:
 
 Good soil 
 Ideal sunlight 
 Strong genetics 
 Any other factor

SUFFICIENT ≠ NECESSARY 
">2x rain always makes you tall" does NOT mean "you need >2x rain to be tall"

Why (D) Fails - Assumes Rainfall is the ONLY Factor: 
 Option D claims: Same height → must have received same rainfall
 Problem #1:  The passage says more rain  TENDS  to make plants taller - it's a tendency, not an absolute rule.
 Problem #2:  Even if it were absolute, same output ≠ same input.
Example:
 
 Group 1:  1.3x  rainfall + poor soil → average height 
 Group 2:  1.0x  rainfall + great soil → average height  
Same height, different rainfall. Rainfall isn't the  only  thing affecting height.

Why (E) Works - Forward Chain: 
  Step 1:  >2x rainfall → above-average height ✓ (given as ALWAYS) 
 Step 2:  Above-average height → above-average taproot ✓ (because taproot = 1⁄2 height) 
 Step 3:  Above-average taproot > average taproot ✓ (by definition)

Each step follows  forward  through guaranteed relationships. No reversal.

The Complete Rule for Must Be True: 
  TRAP:  Reversing conditionals (A→B becomes B→A) 
 TRAP:  Claiming "likely" without probability data 
 VALID:  Forward chains through guarantees (A→B→C)

False chicory's taproot is always one half as long as the plant is tal

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False chicory's taproot is always one half as long as the plant is tal

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