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If n is an integer and n^3 is between 1 and 100, inclusive [#permalink]
 19 Oct 2010, 11:25
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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. Need help on this question which is explained in the Number Properties book by Manhattan. According to Manhattan, the OA is C, but to me, the OA should be A. We know that n>0 because n^3 is between 1 and 100, so n is a positive integer. The value of n could be 1, 2, 3, and 4. Statement 1: n = 2k+1. So n is an odd number. So n is either 1 or 3. According to MGMAT, statement 1 is not sufficient to answer the question because n could be either 1 or 3 and so there is not a unique value of n as it yields two possible values. But this is where I beg to differ. According to me, the value of n could be only 3 (n = 2*1+1). Tell me where I am wrong.
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Re: DS: MGMAT Number Properties [#permalink]
19 Oct 2010, 12:00
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shekharvineet wrote: Need help on this question which is explained in the Number Properties book by Manhattan. According to Manhattan, the OA is C, but to me, the OA should be A.
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.
We know that n>0 because n^3 is between 1 and 100, so n is a positive integer. The value of n could be 1, 2, 3, and 4.
Statement 1: n = 2k+1. So n is an odd number. So n is either 1 or 3. According to MGMAT, statement 1 is not sufficient to answer the question because n could be either 1 or 3 and so there is not a unique value of n as it yields two possible values. But this is where I beg to differ. According to me, the value of n could be only 3 (n = 2*1+1).
Tell me where I am wrong. If n is an integer and n^3 is between 1 and 100, inclusive, what is the value of n?n is an integer and n^3 is between 1 and 100, inclusive, means that n could be 1, 2, 3 or 4 (but not 5 or more since 5^3=125>100). (1) n = 2k+1, where k is an integer --> n is an odd number --> n could be 1 or 3. Not sufficient. (2) n is a prime number --> n could be 2 or 3. Not sufficient. (1)+(2) n could be only 3. Sufficient. Answer: C. As for your doubt: n=2k+1, where k is an integer is a fromula of odd number so you can get ANY odd number with it, including 1: if k=0 then n=2k+1=1. Hope it helps.
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Re: DS: MGMAT Number Properties [#permalink]
19 Oct 2010, 12:21
Thanks.
It cleared my doubt, especially the last part in your solution where you talk about the value of the integer k. I simply forgot the fact that 0 is and integer and so n could be 1 or 3. thats the reason why I was getting 3 as the only value of n from the 1st statement.
+1 to you.
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Re: DS: MGMAT Number Properties [#permalink]
20 Oct 2010, 06:11
(1) n = 2k+1, where k is an integer -->
so K can take ----- -4 -3 -2 -1 0 1 2 3 4 ----
but if i take any negative it wont be between 1 and 100 as a power cube..
so negative numbers out.
from n = 2K + 1 ===> k should be either 0 or 2 if it is 3 then n =
so i should consider only 0,1,2,3,.....
but n = 2k + 1 and n^3 is between 1 and 100 inclusive... there could be a chance of 2 values for n
if k = 0, then n = 1 ===> n^3 =1 <= 100
K = 1, then n= 3 ===> n^3 = 27 <= 100
k = 2 then n = 5 ====> n^3 = 5^3 = 125 > 100
So from 1 only 2 possible values 1 and 3 for the N
(2) n is a prime number --> could be 2 or 3 -->
So the n value from the both (1) and (2) is 3
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If n is an integer and n^3 is between 1 and 100, inclusive [#permalink]
05 Jun 2012, 11:23
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. que. from manhattangmat number properties page 100.... can anybody provide the solution to this problem.....i am having doubt in this problem...
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Re: doubt on question from manhattangmat book number properties [#permalink]
05 Jun 2012, 12:34
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given n*n*n = inclusive 1 - 100
St.1 ) n = 2k+1
implies n is odd and n*n*n = 1 - 100,
n= 1, 3 - NOT sufficient
St.2) n=prime no.
implies n= 2,3 (as again n*n*n = 1- 100) NOT sufficient
St.1) and St. 2) = 3, sufficient.
Answer - C
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Re: doubt on question from manhattangmat book number properties [#permalink]
05 Jun 2012, 14:40
kashishh wrote: given n*n*n = inclusive 1 - 100
St.1 ) n = 2k+1
implies n is odd and n*n*n = 1 - 100,
n= 1, 3 - NOT sufficient
St.2) n=prime no.
implies n= 2,3 (as again n*n*n = 1- 100) NOT sufficient
St.1) and St. 2) = 3, sufficient.
Answer - C thanks a lot......i need 1 more help....while solving quant section,most of my questions on inequalities,probablity,standard deviation etc are always gettin wrong....ny idea from where should i study these...... regards, mudit
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Number properties question from GMAT manhattan [#permalink]
10 Jun 2012, 04:00
If n is an integer and n^3 is between 1 and 100 inclusive. What is the value of n? (a) n = 2k+1 where k is an integer (b) n is a prime number This where I get confused as the answer is C. Both statements are together sufficient. But Shouldn't it be A? Since according to (a), n is at least 3 and odd. Thus it cant be 5x5x5=125 (it's to much), 4x4x 4= 64 (not odd), 2x2x2= 16 (must be higher) same goes for 1x1x1.
so according to (a). K can only be 1. which makes n = 3.
So what have I missed here since the official answer is (C) that both are together sufficient. Why would I need to know that n is a prime number since that can be derived from (a) |
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Re: Number properties question from GMAT manhattan [#permalink]
10 Jun 2012, 04:04
jonatande wrote: If n is an integer and n^3 is between 1 and 100 inclusive. What is the value of n? (a) n = 2k+1 where k is an integer (b) n is a prime number This where I get confused as the answer is C. Both statements are together sufficient. But Shouldn't it be A? Since according to (a), n is at least 3 and odd. Thus it cant be 5x5x5=125 (it's to much), 4x4x 4= 64 (not odd), 2x2x2= 16 (must be higher) same goes for 1x1x1.
so according to (a). K can only be 1. which makes n = 3.
So what have I missed here since the official answer is (C) that both are together sufficient. Why would I need to know that n is a prime number since that can be derived from (a) Merging similar topics. Please ask if anything remains unclear. P.S. Please read and follow: 11-rules-for-posting-133935.html
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Re: Number properties question from GMAT manhattan
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10 Jun 2012, 04:04
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