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

 It is currently 15 Dec 2019, 11:04

### 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

# If x =-100^1/3*100^3 , then the value of 1/x is

Author Message
TAGS:

### Hide Tags

Manager
Status: Never ever give up on yourself.Period.
Joined: 23 Aug 2012
Posts: 130
Location: India
Concentration: Finance, Human Resources
GMAT 1: 570 Q47 V21
GMAT 2: 690 Q50 V33
GPA: 3.5
WE: Information Technology (Investment Banking)
If x =-100^1/3*100^3 , then the value of 1/x is  [#permalink]

### Show Tags

14 Jan 2013, 06:51
1
12
00:00

Difficulty:

75% (hard)

Question Stats:

60% (02:27) correct 40% (02:18) wrong based on 197 sessions

### HideShow timer Statistics

If x =$$-100^{1/3}*100^3$$ , then the value of 1/x is

A. between −5×10^6 and −4×10^6

B. between −2.5×10^−7 and −2×10^−7

C. equal to −100

D. between 2×10^−7 and 2.5×10^−7

E. between 4×10^6 and 5×10^6

_________________
Don't give up on yourself ever. Period.
Beat it, no one wants to be defeated (My journey from 570 to 690) : http://gmatclub.com/forum/beat-it-no-one-wants-to-be-defeated-journey-570-to-149968.html
Senior Manager
Joined: 20 Aug 2015
Posts: 384
Location: India
GMAT 1: 760 Q50 V44
Re: If x =-100^1/3*100^3 , then the value of 1/x is  [#permalink]

### Show Tags

21 Oct 2015, 04:50
1
LaxAvenger wrote:
Thanks, but my question was more aiming on whether we are actually expecting to see such a question on the real exam ?

Best regards,
Lax

No ... the questions on the GMAT would not require you to solve for cube root of 100.
Knowing the square roots should suffice.
Math Expert
Joined: 02 Sep 2009
Posts: 59730
Re: If x =-100^1/3*100^3 , then the value of 1/x is  [#permalink]

### Show Tags

14 Jan 2013, 07:19
daviesj wrote:
If x =$$-100^{1/3}*100^3$$ , then the value of 1/x is

A. between −5×10^6 and −4×10^6

B. between −2.5×10^−7 and −2×10^−7

C. equal to −100

D. between 2×10^−7 and 2.5×10^−7

E. between 4×10^6 and 5×10^6

$$-\sqrt[3]{100}$$ a bit more than -5 and is a bit less than -4 (-5^3=-125 and -4^3=-64). Actually $$-\sqrt[3]{100}\approx{-4.6}$$

So, $$-5*100^3<x<-4*100^3$$ --> $$-5*10^6<x<-4*10^6$$ --> $$\frac{1}{-4*10^6}<\frac{1}{x}<\frac{1}{-5*10^6}$$ --> $$\frac{1}{-0.4*10^7}<\frac{1}{x}<\frac{1}{-0.5*10^7}$$ --> $$-2.5*10^{-7}<\frac{1}{x}<-2*10^{-7}$$.

Hope it's clear.
_________________
Intern
Joined: 06 Sep 2014
Posts: 10
Location: India
Concentration: General Management, Strategy
GMAT 1: 710 Q47 V40
GPA: 3.8
WE: Consulting (Computer Software)
Re: If x =-100^1/3*100^3 , then the value of 1/x is  [#permalink]

### Show Tags

03 Oct 2015, 05:56
daviesj wrote:
If x =$$-100^{1/3}*100^3$$ , then the value of 1/x is

A. between −5×10^6 and −4×10^6

B. between −2.5×10^−7 and −2×10^−7

C. equal to −100

D. between 2×10^−7 and 2.5×10^−7

E. between 4×10^6 and 5×10^6

Can this be solved in the following way? POE which is faster....

Solve for x = -10 ^ 20/3 which is ~ -10 ^ 6.66

Therefore, 1/x = - 1/10 ^ -6.66

Of the options, only one range is both -ve in sign and power of 10 .... Hence, B
Manager
Joined: 18 Aug 2014
Posts: 111
Location: Hong Kong
Schools: Mannheim
Re: If x =-100^1/3*100^3 , then the value of 1/x is  [#permalink]

### Show Tags

20 Oct 2015, 12:41
Bunuel wrote:
daviesj wrote:
If x =$$-100^{1/3}*100^3$$ , then the value of 1/x is

A. between −5×10^6 and −4×10^6

B. between −2.5×10^−7 and −2×10^−7

C. equal to −100

D. between 2×10^−7 and 2.5×10^−7

E. between 4×10^6 and 5×10^6

$$-\sqrt[3]{100}$$ a bit more than -5 and is a bit less than -4 (-5^3=-125 and -4^3=-64). Actually $$-\sqrt[3]{100}\approx{-4.6}$$

So, $$-5*100^3<x<-4*100^3$$ --> $$-5*10^6<x<-4*10^6$$ --> $$\frac{1}{-4*10^6}<\frac{1}{x}<\frac{1}{-5*10^6}$$ --> $$\frac{1}{-0.4*10^7}<\frac{1}{x}<\frac{1}{-0.5*10^7}$$ --> $$-2.5*10^{-7}<\frac{1}{x}<-2*10^{-7}$$.

Hope it's clear.

Do we need to know the approx. value of 3rd root of 100 for the actual gmat??
Senior Manager
Joined: 20 Aug 2015
Posts: 384
Location: India
GMAT 1: 760 Q50 V44
Re: If x =-100^1/3*100^3 , then the value of 1/x is  [#permalink]

### Show Tags

21 Oct 2015, 04:01
LaxAvenger wrote:
Bunuel wrote:
daviesj wrote:
If x =$$-100^{1/3}*100^3$$ , then the value of 1/x is

A. between −5×10^6 and −4×10^6

B. between −2.5×10^−7 and −2×10^−7

C. equal to −100

D. between 2×10^−7 and 2.5×10^−7

E. between 4×10^6 and 5×10^6

$$-\sqrt[3]{100}$$ a bit more than -5 and is a bit less than -4 (-5^3=-125 and -4^3=-64). Actually $$-\sqrt[3]{100}\approx{-4.6}$$

So, $$-5*100^3<x<-4*100^3$$ --> $$-5*10^6<x<-4*10^6$$ --> $$\frac{1}{-4*10^6}<\frac{1}{x}<\frac{1}{-5*10^6}$$ --> $$\frac{1}{-0.4*10^7}<\frac{1}{x}<\frac{1}{-0.5*10^7}$$ --> $$-2.5*10^{-7}<\frac{1}{x}<-2*10^{-7}$$.

Hope it's clear.

Do we need to know the approx. value of 3rd root of 100 for the actual gmat??

Not necessarily. You can always approximate the value.
The cube of 4 is 64 and the cube of 5 is 125.
Hence the value will lie somewhere between 4 and 5.

If you see closely, the value will be north of 4.5 as 100 is closer to 125 than to 64.

Does this help?
Manager
Joined: 18 Aug 2014
Posts: 111
Location: Hong Kong
Schools: Mannheim
Re: If x =-100^1/3*100^3 , then the value of 1/x is  [#permalink]

### Show Tags

21 Oct 2015, 04:14
Thanks, but my question was more aiming on whether we are actually expecting to see such a question on the real exam ?

Best regards,
Lax
Manager
Joined: 17 Mar 2015
Posts: 113
If x =-100^1/3*100^3 , then the value of 1/x is  [#permalink]

### Show Tags

29 Oct 2015, 05:10
I solved this question by simply removing the obviously wrong answers:
$$\frac{1}{x} = -100^{\frac{-1}{3}}*100^{-3} = 10^{-7}*\sqrt[3]{10}$$
Now what we got:
C D and E are out coz number is negaitve
power of A is just to low so its an easy B w/o thinking really coz $$\sqrt[3]{10}$$ isn't big enough to change power.
Non-Human User
Joined: 09 Sep 2013
Posts: 13743
Re: If x =-100^1/3*100^3 , then the value of 1/x is  [#permalink]

### Show Tags

14 Oct 2019, 01:46
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.
_________________
Re: If x =-100^1/3*100^3 , then the value of 1/x is   [#permalink] 14 Oct 2019, 01:46
Display posts from previous: Sort by