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GMAT Club Olympics 2025 (Day 4): African grey parrots cannot detect

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BeachStudy

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03 Jul 2025, 09:32

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Notes:
Wavelengths must be less than 620 NM

Question:
Can it detect W?

1) Color V is 300 ---- We still dont know Color W. So not sufficient
2) W is twice V ----- alone this is not sufficient

Combined) We know W = 2V and V=300 so W is 600. Yes we can solve for W and know if it is detectible.

C) When together this is enough information!

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First statement gives only informations about color V and not color W ---> insufficient
Second statement gives only a ratio between the two colors. Without any measurements information the statement is insufficient.
When we combine the two statements : V=300 nanometers and W =2*V = 2*300= 600 ---> This is sufficient to answer the question so option C.

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Colours with
Wavelength >= 620nm

Can an African grey parrot detect color W?:
To check: Wavelenght of W >=620nm or not?

1) V = 300nm
No information about wavelength of W
INSUFFICIENT

2) W = 2V

INSUFFICIENT - No way to deduce the wavelength of W from just this information

Combined 1 & 2

V = 300

W = 2V = 600
which is enough information to ask the question -> OPTION C

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African grey parrots cannot see colors with wavelengths of 620 nanometers or more. Statement (1) says color V has a wavelength of 300 nm, but it doesn’t tell us anything about color W, so it's not enough. Statement (2) says color W has twice the wavelength of color V, but without knowing color V’s wavelength, this also isn’t enough.

Together, they help: if color V is 300 nm, then color W is 2 × 300 = 600 nm. Since 600 nm is less than 620 nm, the parrot can detect color W. So, both statements together are needed to answer the question. Answer: C.

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1. Colour V has a wavelength of 300 nm.
This tells us nothing about colour W, so we cannot answer the question.
Not sufficient

2. The wavelength of colour W is twice that of colour V.
Still, we don’t know the actual value of either colour V or W.
Not sufficient

From (1), colour V = 300 nm
From (2), colour W = 2 × 300 = 600 nm

Since 600 < 620, the African grey parrot can detect colour W.

Together sufficient

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African grey parrots cannot detect colors with wavelengths greater than or equal to 620 nanometers. Can an African grey parrot detect color W?
The question: is W <620?

(1) only: Color V has a wavelength of 300 nanometers.
Can't tell

(2) only: The wavelength of color W is twice that of color V.
Can't tell

Both (1) & (2): W = 2V = 600 <620

Answer: C

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Statements:

Color V has wavelength 300 nm.
we don't know anything about W.
Wavelength of color W is twice that of V.
How much is V? we don't know.

Combining both:
W = 2 × 300 nm = 600 nm
Since 600 nm is below 620 nm, it falls within the detectable range (< 620 nm).

Therefore:
Yes, an African grey parrot can detect color W. So
C) Both together are sufficient.

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African grey parrots cannot detect colors with wavelengths greater than or equal to 620 nanometers. Can an African grey parrot detect color W?

(1) Color V has a wavelength of 300 nanometers.
(2) The wavelength of color W is twice that of color V.

Statement A: Not Enough since the question is about W and not V, statement doesnt give any detail on wavelength of W
Statement B: W in terms of V is good to have but then we don't have a Value to compare with 620 Nanometers thus not sufficient

Combining A and B, we have W=600 nanometers and hence parrot cannot detect

Answer is C, both statements together is required to answer the question.

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The question is whether a parrot can detect color W. The rule is that it cannot detect wavelengths 620 nm or greater. This means it can detect any wavelength less than 620 nm. We need a definitive "yes" or "no" answer.

Statement (1) gives the wavelength for color V, but not for color W. This is insufficient.

Statement (2) gives a relationship between W and V (W = 2V), but no actual values. We cannot determine W's wavelength. This is insufficient.

Combining both statements, we know V is 300 nm and W is twice V. Therefore, the wavelength of W is 2 * 300 = 600 nm. Since 600 nm is less than the 620 nm threshold, the parrot can detect color W. This gives a definitive "yes" answer.

Because the combined statements are sufficient, but neither is alone, the answer is C.

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Bunuel

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(1) Color V has a wavelength of 300 nanometers.

No information on wavelength of color W. Hence the statement alone is not sufficient.

(2) The wavelength of color W is twice that of color V.

No information on the wavelength of color W. Hence the statement is not sufficient.

(1) + (2)

Wavelength of Color W = 600

We know that African grey parrots cannot detect colors with wavelengths greater than or equal to 620 nanometers, but can they detect wavelengths of 600 nm. We don't know that.

Hence, Option E

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Statement (1) Alone
"Color V has a wavelength of 300 nanometers."

This statement provides information only about color V. It tells us nothing about the wavelength of color W. Therefore, statement (1) alone is insufficient.

Statement (2) Alone
"The wavelength of color W is twice that of color V."

This gives us a relationship: Wavelength(W) = 2 * Wavelength(V). However, without knowing the wavelength of V, we can't determine the wavelength of W.

Scenario 1: If V's wavelength is 200 nm, then W's is 400 nm. The parrot can detect it.

Scenario 2: If V's wavelength is 400 nm, then W's is 800 nm. The parrot cannot detect it.

Since we can't get a definite answer, statement (2) alone is insufficient.

Statements (1) and (2) Together
By combining the statements, we can find the exact wavelength of color W.

From statement (1), the wavelength of color V is 300 nm.

From statement (2), the wavelength of color W is twice that of V.

Therefore, the wavelength of color W is 2 * 300 nm = 600 nm.

Since 600 nm is less than the 620 nm threshold, we can definitively say yes, an African grey parrot can detect color W.

Because we can find a conclusive answer only by using both statements together, the correct choice is C.

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03 Jul 2025, 10:09

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Statement (1):
Color V has a wavelength of 300 nanometers.
This tells us about color V, but nothing about color W, so we can't determine if the parrot can detect color W.
Not sufficient

Statement (2):
The wavelength of color W is twice that of color V.
Again, we know W = 2 × V, but we don't know the value of V.
If V = 200 nm → W = 400 nm → detectable
If V = 400 nm → W = 800 nm → not detectable
Not sufficient

Combine (1) and (2):
From (1): V = 300 nm
From (2): W = 2 × 300 = 600 nm
Now check:
Since 600 nm < 620 nm → Yes, the parrot can detect color W
Sufficient when combined

Answer C

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African grey parrots cannot detect colors with wavelengths greater than or equal to 620 nanometers.
Required: Wavelength of Color W to know if grey parrot can detect the color or not

Statement 1: We don't know the wavelength of color W, hence, not sufficient
Statement 2: We don't know the value of V, therefore, not sufficient

On combining the 2 statements, we know that wavelength of v=300 and w will be 600, hence, sufficient.

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Bunuel

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So Requirement Statement is : Can African grey parrot detect color W?

Give African Grey Parrot CANNOT detection W >= 620 ----- (1)

S1 - V = 300 nm → doesn’t tell us about W → Not enough
S2 - W = 2 × V → but we don’t know V → Not enough

S1 + S2 :
V = 300 nm → W = 2 × 300 = 600 nm

Hence based on the facts the S1+ S2 sufficient.

Answer C. Both statements together are sufficient, but neither alone is sufficient.

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Ans (C)

AGP can detect colours with wavelength >= 620nm
Ques stem: can AGP detect colour W/ what is the wavelength of colour W/ is W>=620

Statement 1 V= 300 nm
We are not given the wavelength of color W.
Not Suffcient.

Statement 2: W=2V
We are not given any values of V or W.
Not Sufficient

Statement 1 and 2
W=600

AGP cannot detect colour W

Sufficient (C)

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Statement 1- It does not tell anything about the wavelength of W. So it is not enough

Statement 2- Wave length of w is twice of v. This does not give any value for wavelength of W.

Both statements combined- Wavelength of w= 2* Wavelength of v= 2*300=600<620 So we can come to conclusion. hence both statements combined are enough.

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(1) => No information about W => Insufficient
(2) => Can determine the wavelengths of W in detailed number => Insufficient
(1) + (2) => W's wavelengths = 2x300=600 < 620 -> African grey parrot can't detect color W => Sufficient

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We need to find if the wavelength of color W, $W_W <620$ nanometers, since under only that circumstance we can say that the parrot can detect color W

Statement 1:
(1) Color V has a wavelength of 300 nanometers.

This only tells us that $W_V = 300$ nanometers. Insufficient.

Statement 2:
(2) The wavelength of color W is twice that of color V.

This tells us that $W_W = 2W_V$. Insufficient.

Statements 1 and 2 together:

We have,
$W_V = 300$ and $W_W = 2W_V$

This tells us that $W_W=600$ nanometers, and since it is $<620$, we can say that the parrot can detect color W. Hence, sufficient.

Answer C.

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(1) Says nothing about W -> INSUFFICIENT

(2) Doesn't provide a numerical value for W -> INSUFFICIENT

(1) + (2):
W = 2*V
V = 300
W = 600

D. Both together.

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Updated on: 04 Jul 2025, 23:46

Originally posted by D3N0 on 03 Jul 2025, 10:37.
Last edited by D3N0 on 04 Jul 2025, 23:46, edited 1 time in total.

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Ans: C

African grey parrots cannot detect colors with wavelengths greater than or equal to 620 nanometers. Can an African grey parrot detect color W?

(1) Color V has a wavelength of 300 nanometers.
This is about V, not W, and the relation is given between V and W [not sufficient]

(2) The wavelength of color W is twice that of color V.
We do not know the wavelength of V or W, so it is not sufficient.

Together: W = 2V
W = 2*300 = 600 which is less than 620 nm [Sufficient]

Note: I was going to mark E as by basic knowledge we know that different colors have different wavelengths. If that parrot can not detect colors >= 620, how do we know which wavelength specifically it can identify? But keeping it simple, choose C

(After looking at the answer explanation, I should have gone with my gut feeling

)

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