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

 It is currently 27 Apr 2015, 16:38

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

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

# If a and b are positive, is (a^-1 + b^-1)^-1 less than

Author Message
TAGS:
Intern
Joined: 19 Aug 2007
Posts: 17
Followers: 0

Kudos [?]: 5 [0], given: 0

If a and b are positive, is (a^-1 + b^-1)^-1 less than [#permalink]  21 Aug 2007, 07:15
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
If a and b are positive, is (a^-1 + b^-1)^-1 less than (a^-1*b^-1)^-1?

(1) a = 2b
(2) a + b > 1

It is really difficult for me.

Thank you for help!

BTW oa is B
Current Student
Joined: 28 Dec 2004
Posts: 3391
Location: New York City
Schools: Wharton'11 HBS'12
Followers: 13

Kudos [?]: 180 [0], given: 2

OK i get B as well..here is how..

the stem simplifys to (ab/(b+a))> ab?

1) a=2b

so we 2b^2/3B > 2b^2?

well if b=1/3 then you gt 2/9=2/9

if b >1/3 then yes ab/(b+a) is less than ab

Insuff

2) a+b>1 well which means ab/(sometheing greater than 1) is < ab

sufficient

B it is...
Manager
Joined: 18 Jun 2007
Posts: 88
Followers: 2

Kudos [?]: 1 [0], given: 0

I got scared initially with the equation as well..But when you simplify it..

ab/ a+b < ab ?

or 1 / a+b <1> 1

So values are 2, 3, 4...

1/2 < 1
1/3 < 1
1/4 < 1

Hence, B is sufficient...
Similar topics Replies Last post
Similar
Topics:
If a and b are positive, is (a^-1 + b^-1) less than 2 20 Aug 2011, 04:03
5 If a and b are positive, is (a^(-1) + b^(-1))^(-1) less than 7 18 Dec 2010, 13:01
If a and b are positive, is (a^(-1) + b^(-1))^(-1) less than 3 07 Nov 2009, 08:39
If a and b are positive, is (a^-1 + b^-1)^-1 less than 6 07 Nov 2006, 10:51
If a and b are positive, is (a^-1 + b^-1)^-1 less than 6 28 May 2006, 22:49
Display posts from previous: Sort by