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

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MBAChaser123

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Statement 1: This statement does not say anything about the color W wavelength, so it's not sufficient.
Statement 2: This statement only gives the ratio about the wavelength of color W and V, which is 2:1, but does not say anything about each one.

Both statements together: if we consider both statements, we can say that the wavelength for color W is 300x2=600 nm

So since W<620, the parrot can detect this color.

Option C is correct.

Bunuel

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.

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Bunuel

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As per the question stem: African Grey Parrots ( AGP) CANNOT detect wavelengths L >= 620 nanometers.

So AGP can detect L up to 619 nanometers.

Can AGP detect color W ?

Statement 1:

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

No specific information about colour W.

Hence insufficient

Statement 2:

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

W = 2*V

two unknown variables. Hence insufficient

Combining Statements 1 and Statements 2, we get

W = 2*V = 2*300 = 600 nanometers.

since, AGP can detect colours of wavelength up to 619.

600 nanometer color W can be detected by AGP.

Hence Sufficient

Option C

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we basically need to know the wavelength of W to tell whether W can be detected or not.

A. Alone V is not gonna help us to determine anything about W (not sufficient)
B B alone also cant help as we do not know the wavelength of V (not sufficient)

A and B together - V = 300, W = 600 which is less than 620 hence can be detected.
sufficient

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Wavelength >= 620 nm, then it can't be detected
So parrot can detect when W<620 nm

1. V 300 nm, but we don't know any relation between color W and V
Not Sufficient
2. Given that W 2V, we don't know the value of V
Not Sufficient

Combined
W = 2v = 2*300
W = 600 <620 can detect
Combined satisfy the condition, Ans C

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Topic(s)- Inequalities
Variables- Color = "C"; Color W = subscript "W"; Color V = subscript "V"
Rephrase Question- Is Cw <= 620 nm?

(1)
Cv = 300 nm
Who cares?? Eliminate A,D.

(2)
Cw = 2*(Cv)
I really care about Cv. What is Cv? Eliminate B.

(3) = (1)+(2)
Oh... now I care AND I know what Cv is.
Cw = 2*(300 nm) <= 620 nm

Answer: C

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Bunuel

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We need to find whether W can be detected,

Stmt (1) Color V has a wavelength of 300 nanometers.
We don't have any connection between V & W hence this is not sufficient.

Stmt (2) The wavelength of color W is twice that of color V.
If the wavelenght is twice fine, We don't now the values, Hence this is also not sufficient.

By combining both we can know that W wavelength is 600, But we only have data about wavelength >=620 => Cannot detect. But we don't have the converse. Hence, if wavelength is <600, but some other condition can contribute to non-detection.

Hence IMO E

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Can an African grey parrot detect color W?

(1) Color V has a wavelength of 300 nanometers.
This gives information about color V, but nothing about W.--> not sufficent

(2) The wavelength of color W is twice that of color V.
This tells us the relationship between W and V, but we don't know V's actual value. --> not sufficent

(1)+(2) we know V=300 and W=2V --> = 600. Sufficent --> C

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03 Jul 2025, 11:28

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Solution:

(1) Color V has a wavelength of 300 nanometers. Not sufficient

(2) The wavelength of color W is twice that of color V. Not sufficient

By combining both statements we get w = 2v = 2(300) = 600 Sufficient

Hence, option C

Bunuel

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statement 1: tells us nothing about color W --> insufficient

statement 2:
provides count info on W, but provides that info in relation to another variable that we know nothing about -- i.e., we are supposed to forget everything from statement 1. --> insufficient

Together,
W= 2V = 2 x 300 = 600, sufficient to determine that African grey parrots can detect color W -- > sufficient --> C

Bunuel

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Given:

African grey parrots cannot detect colors with wavelengths ≥ 620 nanometers
This means they CAN detect colors with wavelengths < 620 nanometers

Statement (1): Color V has a wavelength of 300 nanometers.
This tells me about color V, but nothing about color W. I cannot determine color W's wavelength from this alone.
Statement (1) alone is insufficient.

Statement (2): The wavelength of color W is twice that of color V.
This gives a relationship between W and V, but without knowing V's wavelength, we cannot determine W's specific wavelength.
Statement (2) alone is insufficient.

Both statements together:

From (1): Color V has wavelength = 300 nm
From (2): Color W's wavelength = 2 × Color V's wavelength
Therefore: Color W's wavelength = 2 × 300 = 600 nm

Since 600 nm < 620 nm, an African grey parrot CAN detect color W.

Answer: C

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IMO Answer is C

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

So we have to see if we can find out the value of W and whether is less than or greater than equal to 620 nanometers.

Statement(1) Color V has a wavelength of 300 nanometers.- INSUFFICIENT as there is no information about W

Statement (2) The wavelength of color W is twice that of color V -INSUFFICEIENT- as there is no values for V and W.

Both the Statements together gives us that W=2V=2*300=600 nanometers.
SUFFICIENT

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Bunuel

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Not sure if I am dreaming but this question seems way too easy.. but answer is C

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Solution approach: Simple math

Question: Is W ≥ 620?

I - V = 300 -> Not suf
II - W = 2V -> Not suf

Together: W = 2V = 600 -> Suf -> 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.
(2) The wavelength of color W is twice that of color V.

LucasH20

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In this DI question we try to give a definitive answer to the question W >= 620? Statement 1 is clearly insufficient because it doesn't provide information on wavelength of the color W. Statement 2 provides us with a comparison to the wavelength of color V but using this statement alone we again can't determine a definitive answer. Using the statements together we can determine W, based on the fact that we have the length of V to be 300 and know that W's length is twice the wavelength of V, therefore W is 600 and thus definitive below 620. Answer C.

Regards,
Lucas

Bunuel

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Given: African grey parrots cannot detect colors with wavelengths >= 620 nanometers, which means that they can detect colors with wavelengths <620 nanometers.

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

We do not know how color V's wavelength relates to that of color W's - Not sufficient

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

If color V has wavelength = 500, color W's wavelength = 2 x 500 = 1000 nanometer -> African grey parrot cannot detect color W.
If color V has wavelength = 100, color W's wavelength = 2 x 100 = 200 nanometer -> African grey parrot can detect color W.

Not sufficient

(1) and (2) combined

Color W wavelength = 2 x Color V wavelength = 2 x 300 = 600 nanometer, which is <620 nanometer.

Hence we are able to determine with certainty that African grey parrots can detect color W. - Sufficient

Answer: C

Bunuel

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Statement(1):Color V has a wavelength of 300 nanometers.
Provides no information about color W.

Statement(2):The wavelength of color W is twice that of color V.
Wavelength of color W = 2*Wavelength of V. This statement only gives relation

Combining (1) and (2):
Wavelength of V = 300
==> Wavelength of W = 300*2 = 600nm
As African grey parrots can detect color with wavelength less than 620nm, they can detect wavelength of color W(600nm) as it is below 620nm

So the Statements together are sufficient.Option C

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Bunuel

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(1) This statement is no info about color W. => Not sufficient
(2) This statement did mention about color W; however, no info about what the wavelength of color W is. => Not sufficient

Combine (1) and (2):
We have the wavelength of color W = 2 the wavelength of color V = 2*(300) =600
=> An African Grey Parrot can detect color W

Answer: C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

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Bunuel

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We just have to look out for any informations that hints relations (direct of indirect) regarding the color W.

1) This is a bait. Some people might be to fast assuming, that the W of the question could have been a V and do not relook.
Not sufficient alone. Provides no informations about W.

2) Not sufficient alone, as we dont know any absolute informations to but the relation into context.

Together they are sufficient, as the know, that W = 2*300 =600. Therefore, the parrot cant detect the color.

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For Parrots to detect color, the Wavelength (Wv) of the color should be <=620 nm

We want to know whether an African grey parrot can detect color W. For that, we need to Wv of color W

St.1: Wv of Color V = 300nm. no info on color W. Not sufficient.
St.2: Wv of W = 2 Wv of V. No info on Wv of V. Not sufficient.

Combining St. 1 and 2, we get:

Wv of W = 2*300 = 600 <=620nm

Option C

Bunuel

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