GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 24 Jun 2018, 11:17

### 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 ab=8, then is a > b?

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 46316
If ab=8, then is a > b? [#permalink]

### Show Tags

21 Aug 2017, 05:58
00:00

Difficulty:

45% (medium)

Question Stats:

75% (01:26) correct 25% (01:21) wrong based on 46 sessions

### HideShow timer Statistics

If ab=8, then is a > b?

(1) -3b >= -18

(2) 2b >= 8

_________________
Senior Manager
Joined: 29 Jun 2017
Posts: 499
GPA: 4
WE: Engineering (Transportation)
Re: If ab=8, then is a > b? [#permalink]

### Show Tags

21 Aug 2017, 06:09
1) -3b >= -18, b<=6, if b =5 then a will be less than b, and if b = 2 then a will be more than b, if b = -4 then a will be -2 then a>b therefore A,D eliminated
2) 2b>=8 , b>=4 , if b =4 then a =2 clearly a <b and if b = 8 a =1 there also a< b, and since b is >4 so we will not consider the negative cases of b which is quite obvious and so for statement 2 we are getting definite NO for what is being asked.

_________________

Give Kudos for correct answer and/or if you like the solution.

Director
Joined: 18 Aug 2016
Posts: 634
GMAT 1: 630 Q47 V29
GMAT 2: 740 Q51 V38
If ab=8, then is a > b? [#permalink]

### Show Tags

21 Aug 2017, 23:04
Bunuel wrote:
If ab=8, then is a > b?

(1) -3b >= -18

(2) 2b >= 8

(1) tells us b<=6....(a,b) can take a lot of values (2,4). (-1,-8),(-8,-1) and (4,2) different answers..not sufficient

(2) tells us b>=4...here b will always be 4 or more than 4..sufficient as a will always be less than b for equation to follow since b is greater than $$\sqrt{8}$$ and is non-negative
Sufficient

B
_________________

We must try to achieve the best within us

Thanks
Luckisnoexcuse

Senior Manager
Joined: 29 Jun 2017
Posts: 499
GPA: 4
WE: Engineering (Transportation)
Re: If ab=8, then is a > b? [#permalink]

### Show Tags

22 Aug 2017, 00:04
Luckisnoexcuse wrote:
Bunuel wrote:
If ab=8, then is a > b?

(1) -3b >= -18

(2) 2b >= 8

(1) tells us b<=6....(a,b) can take a lot of values (2,4). (-1,-8),(-8,-1) and (4,2) different answers..not sufficient

(2) tells us b>=4...here b will always be 4 or more than 4..sufficient as a will always be less than b for equation to follow since b is greater than $$\sqrt{8}$$ and is non-negative
Sufficient

B

How you got b>√8 kindly elaborate??? or in line 2 may be you wrote by mistake, as by statement 2 i got b>=4 not less than that ??
_________________

Give Kudos for correct answer and/or if you like the solution.

Director
Joined: 18 Aug 2016
Posts: 634
GMAT 1: 630 Q47 V29
GMAT 2: 740 Q51 V38
Re: If ab=8, then is a > b? [#permalink]

### Show Tags

22 Aug 2017, 00:08
sahilvijay wrote:
Luckisnoexcuse wrote:
Bunuel wrote:
If ab=8, then is a > b?

(1) -3b >= -18

(2) 2b >= 8

(1) tells us b<=6....(a,b) can take a lot of values (2,4). (-1,-8),(-8,-1) and (4,2) different answers..not sufficient

(2) tells us b>=4...here b will always be 4 or more than 4..sufficient as a will always be less than b for equation to follow since b is greater than $$\sqrt{8}$$ and is non-negative
Sufficient

B

How you got b>√8 kindly elaborate??? or in line 2 may be you wrote by mistake, as by statement 2 i got b>=4 not less than that ??

that was a thought process as b>=4(which is greater than √8 ) since both have to be positive (or both will be negative which we cannot take as b>=4)
the critical point for a=b=√8 and since b is greater than the critical point...automatically it implies that a will be smaller(positive)
_________________

We must try to achieve the best within us

Thanks
Luckisnoexcuse

Senior Manager
Joined: 29 Jun 2017
Posts: 499
GPA: 4
WE: Engineering (Transportation)
Re: If ab=8, then is a > b? [#permalink]

### Show Tags

22 Aug 2017, 00:20
okay Luckisnoexcuse
_________________

Give Kudos for correct answer and/or if you like the solution.

SVP
Joined: 26 Mar 2013
Posts: 1677
Re: If ab=8, then is a > b? [#permalink]

### Show Tags

22 Aug 2017, 03:56
If ab=8, then is a > b?

(1) -3b >= -18

Divide by -3 and flip the sign...then $$x\leq{6}$$

Let b = 6 ......a = 3/4.....Answer is No

Let b = -8......a = -1.......Answer is Yes

Insufficient

(2) 2b >= 8

Divide by 2 (no flip of sign)....then $$x\geq{4}$$

Let Let b = 4 ......a = 2.....Answer is No

Let b = 6 ......a = 3/4.....Answer is No

As b is positive number getting greater, a is positive number getting smaller........Answer is Always NO

Sufficient

Re: If ab=8, then is a > b?   [#permalink] 22 Aug 2017, 03:56
Display posts from previous: Sort by