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If n is a positive integer and k = 5.1 x 10^n , what is the
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Updated on: 18 Dec 2012, 08:21
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Originally posted by Baten80 on 09 Mar 2011, 07:52.
Last edited by Bunuel on 18 Dec 2012, 08:21, edited 2 times in total.
Renamed the topic and edited the question.




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Re: Arithmetic properties
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09 Mar 2011, 08:07
Baten80 wrote: If n is a positive integer and k = 5.1 x^n , what is the value of k ? (1) 6,000 < k < 500,000 (2) k^2 = 2.601 * 10^9
I understand the official explanation. is there any other easy way? Question should read: If n is a positive integer and k = 5.1 * 10^n, what is the value of k ?As n is a positive integer then k could be: 51, 510, 5,100, 51,000, ... Also note that no matter the value of n, k is always a positive number. (1) 6,000 < k < 500,000 > only one number from above is in this range: 51,000. Sufficient. (2) k^2 = 2.601 * 10^9 > we can solve quadratics to get two values of k positive and negative, but since given that k is positive then only the positive value of k will be valid. Sufficient. Answer: D.
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Re: Arithmetic properties
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09 Mar 2011, 08:31
Bunuel wrote: Baten80 wrote: If n is a positive integer and k = 5.1 x^n , what is the value of k ? (1) 6,000 < k < 500,000 (2) k^2 = 2.601 * 10^9
I understand the official explanation. is there any other easy way? Question should read: If n is a positive integer and k = 5.1 * 10^n, what is the value of k ?As n is a positive integer then k could be: 51, 510, 5,100, 51,000, ... Also note that no matter the value of n, k is always a positive number. (1) 6,000 < k < 500,000 > only one number from above is in this range: 51,000. Sufficient. (2) k^2 = 2.601 * 10^9 > we can solve quadratics to get two values of k positive and negative, but since given that k is positive then only the positive value of k will be valid. Sufficient. Answer: D. I corrected the original post.
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If n is a positive integer and k = 5.1 x 10^n , what is the valu
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23 Jul 2015, 13:47
Actually the answer D is correct.
Allow me to explain. As n is a positive integer. The values of k will be
n=1 > 51 n+2 > 510 n+3 > 5,100 n+4 > 51,000 n+5 > 510,000
The inequality,although very wide,tells us about the only possible value of k which is 51,000. As 5100 is less than 6000 and 510,000 is more than 500,000.
Statement B is sufficient on its own. Should give a positive and negative value of K. But the question stem tells us that K is positive.
Hope this helps



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Re: If n is a positive integer and k = 5.1 x 10^n , what is the
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16 Jul 2016, 06:34
Bunuel wrote: Baten80 wrote: If n is a positive integer and k = 5.1 x^n , what is the value of k ? (1) 6,000 < k < 500,000 (2) k^2 = 2.601 * 10^9
I understand the official explanation. is there any other easy way? Question should read: If n is a positive integer and k = 5.1 * 10^n, what is the value of k ?As n is a positive integer then k could be: 51, 510, 5,100, 51,000, ... Also note that no matter the value of n, k is always a positive number. (1) 6,000 < k < 500,000 > only one number from above is in this range: 51,000. Sufficient. (2) k^2 = 2.601 * 10^9 > we can solve quadratics to get two values of k positive and negative, but since given that k is positive then only the positive value of k will be valid. Sufficient. Answer: D. could you please explain the solution of statement 2



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Re: If n is a positive integer and k = 5.1 x 10^n , what is the
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16 Jul 2016, 08:38
Maruf Iqbal wrote: Bunuel wrote: Baten80 wrote: If n is a positive integer and k = 5.1 x^n , what is the value of k ? (1) 6,000 < k < 500,000 (2) k^2 = 2.601 * 10^9
I understand the official explanation. is there any other easy way? Question should read: If n is a positive integer and k = 5.1 * 10^n, what is the value of k ?As n is a positive integer then k could be: 51, 510, 5,100, 51,000, ... Also note that no matter the value of n, k is always a positive number. (1) 6,000 < k < 500,000 > only one number from above is in this range: 51,000. Sufficient. (2) k^2 = 2.601 * 10^9 > we can solve quadratics to get two values of k positive and negative, but since given that k is positive then only the positive value of k will be valid. Sufficient. Answer: D. could you please explain the solution of statement 2 \(k^2 = 2.601 * 10^9 = 2601*10^6 = 51^2*(10^3)^2\) \(k= \sqrt{51^2*(10^3)^2}=51*10^3=51000\)
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If n is a positive integer and k = 5.1 x 10^n , what is the
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23 Sep 2016, 09:35
D is the correct answer. Here's why:
(1) 6,000 < k < 500,000 > n=4 because other values would put k outside of its 'bounds' that we are given with (1).
SUFFICIENT
(2) k^2 = 2.601 * 10^9 > square root both sides to get k alone and set RHS equal to main equation and solve for n.
SUFFICIENT



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Re: If n is a positive integer and k = 5.1 x 10^n , what is the
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23 Feb 2017, 06:01
Prompt analysis K is a positive integer Superset The value of n could be any positive integer Translation In order to the value on n, we need: 1# exact value of n 2# range of k 3# any equation to find the value of n Statement analysis St 1: from the range, the value of n comes out to be 4. ANSWER. Hence option b,c,e eliminated St 2: from the statement we get k = 5.1 x 10^4. Since k is positive, we can say that the value of n is 4. ANSWER Option D.
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Re: If n is a positive integer and k = 5.1 x 10^n , what is the
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12 Sep 2017, 10:14
Bunnel, This might sound very basic..but I had to ask to be a 100% about my understanding.. So u have mentioned in the highlighted text below that no matter the value of n, k is always positive.. Could please explain that? Values means = + or  or do u mean the power of 10? Thanks in advance! Shirai Bunuel wrote: Baten80 wrote: If n is a positive integer and k = 5.1 x^n , what is the value of k ? (1) 6,000 < k < 500,000 (2) k^2 = 2.601 * 10^9
I understand the official explanation. is there any other easy way? Question should read: If n is a positive integer and k = 5.1 * 10^n, what is the value of k ?As n is a positive integer then k could be: 51, 510, 5,100, 51,000, ... Also note that no matter the value of n, k is always a positive number.(1) 6,000 < k < 500,000 > only one number from above is in this range: 51,000. Sufficient. (2) k^2 = 2.601 * 10^9 > we can solve quadratics to get two values of k positive and negative, but since given that k is positive then only the positive value of k will be valid. Sufficient. Answer: D.



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Re: If n is a positive integer and k = 5.1 x 10^n , what is the
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12 Sep 2017, 10:23
shinrai15 wrote: Bunnel, This might sound very basic..but I had to ask to be a 100% about my understanding.. So u have mentioned in the highlighted text below that no matter the value of n, k is always positive.. Could please explain that? Values means = + or  or do u mean the power of 10?Thanks in advance! Shirai Bunuel wrote: Baten80 wrote: If n is a positive integer and k = 5.1 x^n , what is the value of k ? (1) 6,000 < k < 500,000 (2) k^2 = 2.601 * 10^9
I understand the official explanation. is there any other easy way? Question should read: If n is a positive integer and k = 5.1 * 10^n, what is the value of k ?As n is a positive integer then k could be: 51, 510, 5,100, 51,000, ... Also note that no matter the value of n, k is always a positive number.(1) 6,000 < k < 500,000 > only one number from above is in this range: 51,000. Sufficient. (2) k^2 = 2.601 * 10^9 > we can solve quadratics to get two values of k positive and negative, but since given that k is positive then only the positive value of k will be valid. Sufficient. Answer: D. Don't know what you mean by the highlighted part... We are given that k = 5.1 * 10^n and that n is a positive integer. k could be: 51, 510, 5,100, 51,000, ... as you can see k is always a positive integer.
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Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
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Re: If n is a positive integer and k = 5.1 x 10^n , what is the
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12 Sep 2017, 12:26
I solved first statement this way. Not sure if this is correct. 6*10^3<51*10^(n1)<5*10^5 So I assumed that the value of n (in order to find k) will come from the 10s. So I just considered 10s while solving further. n has to be 5 for the above inequality to be true. 6*10^3<51*10^4<5*10^5 But figured out that this does not make sense as the inequality is not more true. 6000<510000<500000 so n= 4 I prefer what Bunuel has posted. Way better method. This is just something..........
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