Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 20 Dec 2013, 15:25

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# DS... is 5^k less than 1000? 1) 5^(k+1) > 3000 2) 5^(k-1)

Author Message
TAGS:
Current Student
Joined: 28 Dec 2004
Posts: 3420
Location: New York City
Schools: Wharton'11 HBS'12
Followers: 12

Kudos [?]: 141 [0], given: 2

DS... is 5^k less than 1000? 1) 5^(k+1) > 3000 2) 5^(k-1) [#permalink]  24 Jul 2005, 09:24
DS...

is 5^k less than 1000?

1) 5^(k+1) > 3000
2) 5^(k-1) = 5^k-500

pls show working...
Senior Manager
Joined: 29 Jun 2005
Posts: 404
Followers: 1

Kudos [?]: 14 [0], given: 0

The answer is B, isn't it?
Explanation:

_______________
1.
5^(k+1)>3000
5*5^k>3000
5^k>600 where, 600->~625->5^~4, keep in mind, that ~4 is less than 4.
5^k>5^~4
k>~4
If k=4, then 5^k would be less than 1000
If we give k=5, than 5^k would be greater than 1000
Insufficient.

________________
2. 5^(k-1) = 5^k-500
5^k=5*5^k-2500
4*5^k=2500
5^k=625
5^k=5^4
k=4
Sufficient
__________________

It looks harder than it actually is. believe me, this is very easy one to solve, once you understand the conception.
Senior Manager
Joined: 04 May 2005
Posts: 286
Location: CA, USA
Followers: 1

Kudos [?]: 8 [0], given: 0

B

from 1) , get : k>600 not necessarily > 1000
from 2), get : k = 4
Senior Manager
Joined: 29 Nov 2004
Posts: 488
Location: Chicago
Followers: 1

Kudos [?]: 3 [0], given: 0

From condition 2, K = 4, so answer is B
_________________

Fear Mediocrity, Respect Ignorance

Manager
Joined: 04 Mar 2005
Posts: 108
Location: NYC
Followers: 2

Kudos [?]: 2 [0], given: 0

S1 : 5^k > 600 - insuff
S2 : 5^k = 625 Suff
Ans is B
Similar topics Replies Last post
Similar
Topics:
Is 5^k less than 1,000 ? (1) 5^k-1 > 3000 (2) 5^k-1 = 5^k 2 11 Jul 2004, 11:09
Is 5^k less than 1,000? 1) 5^(k-1) > 3,000 2) 5^(k-1) = 7 19 Apr 2006, 19:03
Is 5^k less than 1,000 ? (1) 5^(k-1) > 3000 (2) 5^(k-1) = 2 28 Feb 2007, 21:49
Is 5^k less than 1,000? (1) 5^k+1 > 3000 (2) 5^K-1 = 5^K 4 15 Mar 2007, 12:09
Is 5^k less than 1,000? (1) 5^(k-1) > 3,000 (2) 5^(k-1) = 23 24 Apr 2007, 06:30
Display posts from previous: Sort by