Q. Is 5^k less than 1,000 ?
(1) 5^k-1 > 3000
(2) 5^k-1 = 5^k - 500
OA is B. Can someone please explain?
Regards
MSD
Gmat Plus DS
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Statement Imsd_2008 wrote:Q. Is 5^k less than 1,000 ?
(1) 5^k-1 > 3000
(2) 5^k-1 = 5^k - 500
OA is B. Can someone please explain?
Regards
MSD
5^k-1 > 3000
5^k/5 > 3000
5^k > 3000*5
Sufficient.
Statement II
5^k/5 = 5^k - 500
5^k = 5^k+1 - 2500
2500 = 5^k 4
5^k = 2500/4
5^k = 625
sufficient.
The 2 statements are contradicting each other which cannot be possible
I guess statement I should be 5^k+1 > 3000, this way
5^k * 5 >3000
5^k > 600
If this the statement I , then answer is B, if not then answer is D.
Hope this helps.
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I think I had this question on a practice test. You may have gotten the direction of the inequality wrong in statement 1. Otherwise, I agree that the answer is D.
Not to mention that as written, the statements contradict one another (5^k=625 and 5^k>15000), which the GMAT does not do.
Not to mention that as written, the statements contradict one another (5^k=625 and 5^k>15000), which the GMAT does not do.
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Here is the link to the correct question
https://www.beatthegmat.com/tough-one-og ... 16616.html
Statement I
5^k+1 > 3000
Hope this helps.
https://www.beatthegmat.com/tough-one-og ... 16616.html
Statement I
5^k+1 > 3000
Hope this helps.
No rest for the Wicked....
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I'm trying a different approach to solution 2. Please comment as to whether this is accurate; Thanks.
5^(k-1)= 5^k - 500
*5^(k-1) is the same as (5^k/5^1)* so
(5^k/5^1) = 5^k - 500
*Next move the 5^K to the left hands side from the right hand side* so
(5^k/5^1) - 5^k = -500
* Then multiply each term by 5 to get rid of the denominator*
5[(5^k/5^1) - 5^k] = 5(-500) so this becomes
5^k - (5^k * 5^1) = -2500 or
5^k - (5^k+1) = -2500
so is this correct so far? How do I then solve for k? Thanks!
5^(k-1)= 5^k - 500
*5^(k-1) is the same as (5^k/5^1)* so
(5^k/5^1) = 5^k - 500
*Next move the 5^K to the left hands side from the right hand side* so
(5^k/5^1) - 5^k = -500
* Then multiply each term by 5 to get rid of the denominator*
5[(5^k/5^1) - 5^k] = 5(-500) so this becomes
5^k - (5^k * 5^1) = -2500 or
5^k - (5^k+1) = -2500
so is this correct so far? How do I then solve for k? Thanks!