It is currently 21 Nov 2017, 21:23

### 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

# Is a > 10?

Author Message
TAGS:

### Hide Tags

Intern
Joined: 05 Nov 2010
Posts: 22

Kudos [?]: 27 [1], given: 0

### Show Tags

07 Nov 2010, 13:45
1
KUDOS
2
This post was
BOOKMARKED
00:00

Difficulty:

45% (medium)

Question Stats:

46% (00:54) correct 54% (00:32) wrong based on 56 sessions

### HideShow timer Statistics

Is a > 10?

(1) 1/a + 1/b = 1/c
(2) 1/a < 1/10
[Reveal] Spoiler: OA

Kudos [?]: 27 [1], given: 0

Math Expert
Joined: 02 Sep 2009
Posts: 42284

Kudos [?]: 132984 [2], given: 12399

### Show Tags

07 Nov 2010, 14:08
2
KUDOS
Expert's post
1
This post was
BOOKMARKED
Creeper300 wrote:
is a>10?

1. 1/a +1/b=1/c
2. 1/a < 1/10

(1) 1/a +1/b=1/c. Clearly insufficient.
(2) 1/a < 1/10 --> a>10 or a<0. Not sufficient.

(1)+(2) Statement (1) is absolutely useless and (2) is not sufficient.

_________________

Kudos [?]: 132984 [2], given: 12399

Manager
Joined: 07 Feb 2010
Posts: 155

Kudos [?]: 769 [0], given: 101

### Show Tags

10 Nov 2010, 06:55
(2) 1/a < 1/10 --> a>10 or a<0. Not sufficient.
BUNUEL PLEASE EXPLAIN ME HOW a<0

Kudos [?]: 769 [0], given: 101

Math Expert
Joined: 02 Sep 2009
Posts: 42284

Kudos [?]: 132984 [2], given: 12399

### Show Tags

10 Nov 2010, 07:24
2
KUDOS
Expert's post
anilnandyala wrote:
(2) 1/a < 1/10 --> a>10 or a<0. Not sufficient.
BUNUEL PLEASE EXPLAIN ME HOW a<0

$$\frac{1}{10}>\frac{1}{a}$$ --> $$\frac{1}{10}-\frac{1}{a}>0$$ --> $$\frac{a-10}{10a}>0$$:

Either both denominator and nominator are positive or both are negative:
$$a>0$$ and $$a-10>0$$, or $$a>10$$ --> $$a>10$$;
$$a<0$$ and $$a-10<0$$, or $$a<10$$ --> $$a<0$$;

So, inequality $$\frac{1}{10}>\frac{1}{a}$$ holds true for: $$a<0$$ and $$a>10$$ (even without the above solution you can spot that when a is negative then 1/a is negative, thus it's less than positive 1/10. Also when a>10, 1/10>1/a).

Hope it's clear.
_________________

Kudos [?]: 132984 [2], given: 12399

Intern
Joined: 28 Oct 2010
Posts: 3

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

### Show Tags

11 Nov 2010, 08:37
1
KUDOS
You can't cross multiply as a can be -ve or +ve. The inequality will change accordingly.

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

Non-Human User
Joined: 09 Sep 2013
Posts: 15573

Kudos [?]: 283 [0], given: 0

Re: Is a > 10? [#permalink]

### Show Tags

29 Sep 2017, 23:48
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

Kudos [?]: 283 [0], given: 0

Re: Is a > 10?   [#permalink] 29 Sep 2017, 23:48
Display posts from previous: Sort by