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

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jipandeyji

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Statement 1 - NS - Only talking about V which has nothing to do with W.

Statement 2 - NS - W= 2V but without knowing V it’s not sufficient.

S1+ S2 = W = 600 which is less than 620. Hence C is sufficient, unless there is a trap which I totally missed.

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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?

We need, w>/= 620nm ?

(1) Color V has a wavelength of 300 nanometers. - How V is related to W? We don't know. [NS]
(2) The wavelength of color W is twice that of color V. - W = 2V, no absolute value to know, how much is the W. [NS]

(1) & (2) - W = 2 * 300 = 600nm => Can detect the color. [S] . Hence, the correct answer is C.

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Given:
Parrots can only detect colors with a wavelength < 620nm.

Statement 1:
Gives no information about W. Insufficient.

Statement 2:
Gives no information about the values of either V or W. Insufficient.

Both together:
V=300nm
Then, W=2x300=600nm, which is less than 620nm. So, parrots can detect colors of wavelength W.

Answer: C(Both statements together are sufficient)

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Bunuel

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Grey Parrots cannot detect wavelength >=620nm
=> For the parrot to detect color W, the wavelength of W must be <620nm.

Statement 1:
Color V has a wavelength of 300 nanometers.
Only tells us about color V.
No info on color W.
Not Sufficient.

Statement 2:
The wavelength of color W is twice that of color V.
Only tells us about the relation of W and V.
Cannot deduce for sure if the wavelength of W> or <=620nm.
Can be true or cannot be true.
Not Sufficient.

Statement 1 and 2 combined:
Now we have V's wavelength =300nm
And W = 2*V
= 600num <620nm
Hence, we get a single answer Yes.
The parrot will be able to detect.
Sufficient.

ANSWER: Option C

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Using the two statements together, we first learn that color V has a wavelength of 300 nm and that color W’s wavelength is twice V’s, so W is 600 nm. Because African grey parrots cannot see wavelengths of 620 nm or higher and 600 nm is below that cutoff, the parrot can detect color W. Neither fact alone tells us W’s actual wavelength, but combined they show that W falls within the bird’s visible range.

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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.

The color detection of African Grey Parrots <=620 nanometers

Question: Can an African grey parrot detect color W? Hence we need to know the wave length of color W.

Statement 1
This provides information on the wavelength of color V not color W. Thus it is insufficient

Statement 2
States a relationship between color V and color W but not the exact wavelength of color W. Thus it is insufficient.

Combined
In statement 1,we know color V= 300 nanometers in wave length.
Statement 2 tells us W= 2V
Thus W= 600
We can therefore provide a definite Yes/ No answer
600<=620. The answer Yes

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not detect if wavelenghts > 620 nanometers

W?

(1)
V=300

No info about W wavelenght

INSUFFICIENT

(2)
W=2V

No info about specific W wavelenght

INSUFFICIENT

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

600<620 so the answer is yes, parrot can detect W

SUFFICIENT

IMO C

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Statement 1 : V's wavelength = 300 nm,
There is nothing about W’s wavelength. Insufficient.

Statement 2 : W's wavelength = 2*(V's wavelength),
We know nothing about V here, so we can’t determine W. Insufficient.

Both statements:
Substituting V = 300 nm in W= 2V
-> W = 2*300 = 600 nm.
Since 600 < 620, the parrot can detect W.
So both statements together are sufficient.

Answer: C.

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Statement 1: Insufficient
Color V = 300 nm, but no info about W. Cannot determine W’s wavelength or detectability.

Statement 2: Insufficient
Wavelength of W = 2 × V, but V is unknown. Cannot find W’s wavelength.

Both statements combined: Sufficient
W = 2 × 300 = 600 nm, which is less than 620 nm. Parrot can detect color W.

Answer: C (Both statements together are sufficient.)

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Given - African grey parrots cannot detect colors with wavelengths greater than or equal to 620 nanometers. Therefore African grey parrots can only detect colors with wavelengths less than 620 nanometers.
To determine - Can African grey parrots detect color W?

Statement 1 - Color V has a wavelength of 300 nanometers.
This tells us nothing about color W. Even if we assumed that there is an ascending or descending pattern going down the english alphabet, we still don't know if wavelength of color W is greater than or less than color V.
Statement 1 is not sufficient.

Statement 2 - The wavelength of color W is twice that of color V.
We have a relationship between color W and color V. But we don't have the magnitude of the wavelength for either.
Statement 2 is not sufficient.

1+2 - V = 300 and W=2V. Therefore W = 2*300 = 600.
600 is less than 620. Therefore the African grey parrot can detect color W.

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

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C. Both Statements are required

Combining the first and second statement we get to know that color W has a wavelength of 600nm which is less than their upper limit.

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For option A, the statement 1 alone is insufficient as there is no information around Color V given in the stimulus & hence option (A) is incorrect

Similarly for option B, the statement 2 alone is insufficient as there is no information around the numerical values of Colors W & V in the stimulus & hence option (B) is incorrect

On combining both the statements, the wavelength of color W is twice that of color V but the wavelength of color V is 300 m which means color W has a wavelength of 600 m but we do not know definitely if the parrots can view wavelengths below 620 meters. So C is not sufficient to answer the question.

Hence option E is the correct answer

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1) no info on W NS
2) no info on V Ns
Combined
W= 2*300=600 which is less than 20 hence cannot detect color w

Suff

Ans C

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Rewriting question: Is the wavelength of W < 620 nm?
(1) It is about wavelength of V, V = 300nm. Not sufficient
(2) W = 2V
(1) + (2) : W = 2(300) = 600. W<620. Sufficient.
Option C

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African grey parrots can't see colors ≥ 620 nm.
Statement 1: Color V = 300 nm

Doesn't tell us about color W
Not enough

Statement 2: Color W = 2 × Color V

Don't know V's wavelength
Not enough

Both together:

V = 300 nm
W = 2 × 300 = 600 nm
600 < 620, so parrot CAN see color W

Need both statements.

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From the given details,
The parrot should be able to see the color if its wavelength is below 620 nanometers
We are supposed to find if the parrot can see a color W.

Considering statement 1,
Color V has a wavelength of 300 nanometers. - While the parrot may be able to see the Color V as its wavelength is < 620 nanometers, this alone does not mention anything about color W. Therefore, this statement alone is not sufficient.

Considering statement 2,
The wavelength of color W is twice that of color V. - This does not mention the wavelengths of colors V or W, Therefore, this statement alone is not sufficient.

Taking both statements 1 & 2 together we have,
Let wavelengths of Color V & Color W be v & w
v = 300 & w = 2 x v

Therefore, w = 600 < 620 nanometers; So the parrot can see color W and both the statements considered together are sufficient.

Correct option is Option C

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Bunuel

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We are solving for the answer W=>620? (1) Not sufficient as it talks about v. (2) not sufficient because we don't know what v is. Together we know what v is and can answer the question. C

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wavelengthens greater or equal to 620 nms, cant be detected, can the parrot detect W.?
1- v has 300 nms, we know nothing about W, not suffient.
2- w=2v. not sufficient
Using both W= 600, now we know that wavelenths greater than or equal to 620 nms cant be detect, but do we have any info about less than 620? No.
So, not sufficient, E.

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(1)
Know only wavelength of V and need wavelength of W

Statement is insufficient

(2)
Know only relation between wavelength of V and wavelength of W, but no actual wavelength of W

Statement is insufficient

(1)+(2)
wavelength of W = 2 * wavelength of V = 2 * 300 = 600

The text says that parrot cannot detect color if wavelength > 620
But it doesn't say anything about if the parrot can detect or not if wavelength <= 620, that is this case.

Both statements are insufficient

The right answer is E

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Bunuel

This question was provided by GMAT Club
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(1) Color V has a wavelength of 300 nanometers.

NOT SUFFICIENT : We are required to determine whether African grey parrot can detect color W.

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

NOT SUFFICIENT : No information is given on the wavelength of color W or of color V.

Combined

Combined we know that the wavelength of color V is 600 nanometers.

However, the premise of the question gives us information on wavelengths the parrot cannot detect. We don't know the wavelengths the parrot can detect.

Option E

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