If n is an integer and n^3 is between 1 and 100, inclusive, what is

Question

If n is an integer and n^3 is between 1 and 100, inclusive, what is the value of n?

(1) n = 2k+1, where k is an integer.
(2) n is a prime number.

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This is an example question from Manhattan Gmat Numbers Properties guide 1. When I initially did the question, I chose statement 1. as sufficient on its own.

Firstly, in the question stem you can narrow down the choices for n as being between 1 and 4. I then tested numbers in the equation in statement 1 and felt able to conclude that n was 3, as plugging any other integers higher than 1 for k made n>4. Statement 2 only allows me to narrow the choice down to 2 or 3 so its insufficient.
BUT when i read through the answer explanation, they dismiss statement 1 as only telling us that n is odd, meaning it leaves us with a choice of 1 or 3, therefore, you'd need both statements to be able to conclude that n was 3.

Could someone tell me where I went wrong?

OPEN DISCUSSION OF THIS QUESTION IS HERE: https://gmatclub.com/forum/if-n-is-an-i ... 03171.html

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Official Answer

C

Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.

For relevant Data Sufficiency questions, please check the Data Sufficiency forum:
Data Sufficiency Forum

schemer · Answer

K can be zero and zero is an integer. Thus, I don't think statement 1 alone is sufficient.

schemer · Answer

k might also have been a negative integer but given that n^3 is between 1 and 100, this part of the number line is ruled out.

meshell · Answer

yes, it can be zero! that'll give me 1 as the answer. 
I guess I'm not out of the habit of think of integers as 1 and beyond. i don't think i'll forget the importance of the almighty zero from now on! thanks for the quick response.

Fistail · Answer

If n is an integer and n^3 is between 1 and 100 inclusive, what is the value of n

From the question n can be only be positive integers: either 1 or 2 or 3 or 4.

(1) If n = 2k +1, where k is an integer:
Here, k can only be 0 and 1 and n could be 1 or 3. not sufficient.

(2) If n is a prime number, n could be 2 or 3.

from 1 and 2, n is 3. So that's C.

DeeptiM · Answer

Can you pls help me understand why K will ONLY b "0" or "1"??

anordinaryguy · Answer

Because possible values of n = 1,2,3,4 (only there cubes will lie between 1 and 100)

and if n = 2k+1 => k = 1 (n = 3), 0 (n=1)

bodleyev · Answer

If n is an integer and n^3 is between 1 and 100 inclusive, what is the value of n?
(1) n= 2k +1, where k is an integer
(2) n is a prime number.

n = -1, n^3 = -1 
 n = 0, n^3 = 0 
n = 1, n^3 = 1
n = 2, n^3 = 8
n = 3, n^3 = 27
n = 4, n^3 = 64
 n = 5, n^3 = 125

1 <= n^3 <= 100, so 1 <= n <= 4.

Rephrase the question stem: "n = 1, 2, 3, or 4. What is n?"

Statement 1) "n is odd", so n could be 1 or 3. Insufficient.

Statement 2) n is prime, so n could be 2 or 3. Insufficient.

Combined) n is an odd prime number, so 3 is the only possibility. Sufficient.

C

LifeChanger · Answer

c..
1. n can be 1 or 3 (when k=0 and 1 repectively)
2.n can be 2,3

combine both stmnts,we have n=3

jansam123 · Answer

Yup .Its C.

We should not miss considering K=0.

Spidy001 · Answer

n is an integer

n^3 lies between 1 and 100.

=> n can only be positive integer and n can be 1 or 2 or 3 or 4

1. Not Sufficient

n is odd integer => n can be 1 or 3

2. Not sufficient

n is 2 or 3

Together,

Its sufficient , n =3.

Answer is C.

DeeptiM · Answer

Ahh..revisited the ques n got to knw d mistake..

Thanks for the explanation..kudos to u!!

crick20002002 · Answer

+1 for C.

Agree with bodleyev's explanation. Kudos to him

Crick

jagdeepsingh1983 · Answer

From Question n^3 is between 1 & 100 so n can not be negative 
now 1^3=1
2^3=8
3^3=27
4^=64
values greater than 4 ruled out
1. n = 2k+1, not sufficient to identify the answer
2. n= Prime number not sufficient to identify the answer

combining both k can be 0 or 1 as we are restricted to values of n=1, 2, 3 & 4 so 4 is also ruled out we are left with 1, 2 & 3 
Now A natural number is called a prime number (or a prime) if it is bigger than one and has no divisors other than 1 and itself.
So left with 2 & 3 
now here k value becomes 1 so answer come to 3

So C is right Answer

Give Kudos if you understood it

Bunuel · Answer

If n is an integer and n^3 is between 1 and 100 inclusive, what is the value of n?
(1) n= 2k +1, where k is an integer
(2) n is a prime number.

[strike]n = -1, n^3 = -1[/strike]
[strike]n = 0, n^3 = 0[/strike]
n = 1, n^3 = 1
n = 2, n^3 = 8
n = 3, n^3 = 27
n = 4, n^3 = 64
[strike]n = 5, n^3 = 125[/strike]

1 <= n^3 <= 100, so 1 <= n <= 4.

Rephrase the question stem: "n = 1, 2, 3, or 4. What is n?"

Statement 1) "n is odd", so n could be 1 or 3. Insufficient.

Statement 2) n is prime, so n could be 2 or 3. Insufficient.

Combined) n is an odd prime number, so 3 is the only possibility. Sufficient.

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C

If n is an integer and n^3 is between 1 and 100, inclusive, what is

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