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

 It is currently 17 Feb 2019, 12:08

### 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 February
PrevNext
SuMoTuWeThFrSa
272829303112
3456789
10111213141516
17181920212223
242526272812
Open Detailed Calendar
• ### Free GMAT Algebra Webinar

February 17, 2019

February 17, 2019

07:00 AM PST

09:00 AM PST

Attend this Free Algebra Webinar and learn how to master Inequalities and Absolute Value problems on GMAT.
• ### Valentine's day SALE is on! 25% off.

February 18, 2019

February 18, 2019

10:00 PM PST

11:00 PM PST

We don’t care what your relationship status this year - we love you just the way you are. AND we want you to crush the GMAT!

# On a scale that measures the intensity of a certain phenomen

Author Message
TAGS:

### Hide Tags

Senior Manager
Joined: 28 Jul 2011
Posts: 343
Location: United States
GPA: 3.86
WE: Accounting (Commercial Banking)
On a scale that measures the intensity of a certain phenomen  [#permalink]

### Show Tags

Updated on: 07 Dec 2012, 05:35
8
60
00:00

Difficulty:

25% (medium)

Question Stats:

73% (01:31) correct 27% (01:56) wrong based on 2124 sessions

### HideShow timer Statistics

On a scale that measures the intensity of a certain phenomenon, a reading of n+1 corresponds to an intensity that is 10 times the intensity corresponding to a reading of n. On that scale, the intensity corresponding to a reading of 8 is how many times as great as the intensity corresponding to a reading of 3?

(A) 5
(B) 50
(C) 10^5
(D) 5^10
(E) 8^10 - 3^10

_________________

Originally posted by mydreammba on 14 Jan 2012, 02:06.
Last edited by Bunuel on 07 Dec 2012, 05:35, edited 2 times in total.
Renamed the topic and edited the question.
Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4486

### Show Tags

13 Mar 2013, 09:24
41
16
abusaleh wrote:
Can anyone give me proper explanation of this question?
On a scale that measures the intensity of a certain phenomenon, a reading of n+1 corresponds to an intensity that is 10 times the intensity corresponding to a reading of n. On that scale, the intensity corresponding to a reading of 8 is how many times as great as the intensity corresponding to a reading of 3?
A) 5
B) 50
C) 10^5
D) 5^10
E) 8^10 - 3^10

Dear abusaleh,
This is a tricky question. It is based on logarithmic scales --- both the Richter scale for earthquakes and the decibel scale for the volume of sound follow this pattern.

It tell us if we we go from n to n+1 on the scale, the intensity is 10 times greater.

Start at 3. If we go from 3 to 4 on the scale, the intensity increases 10 times. Then from 4 to 5, it increases 10 times. Same, from 5 to 6, from 6 to 7, and from 7 to 8. There are five "steps" from 3 to 8, and each one of these steps increases the intensity by a factor of 10. That means, when we go from 3 to 8 on the scale, we multiply the intensity by 10 five times ---- 10*10*10*10*10 = 10^5

Does this make sense?

Mike
_________________

Mike McGarry
Magoosh Test Prep

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)

Intern
Status: ISB 14...:)
Joined: 25 May 2012
Posts: 28
Location: India
Concentration: Strategy
Schools: ISB '14 (A)
GMAT 1: 750 Q51 V39
GPA: 3.62
WE: Engineering (Energy and Utilities)

### Show Tags

07 Jun 2012, 00:52
15
4
As the intensity increases 10 times every time

from 3 to 8, it increases 5 times. So,answer is 10^5
##### General Discussion
Math Expert
Joined: 02 Sep 2009
Posts: 52906
On a scale that measures the intensity of a certain phenomen  [#permalink]

### Show Tags

14 Jan 2012, 03:54
18
25
kotela wrote:
Hey Guys i didn't understand the solution to the problem in OG 12 PS#98, can anyone please explain me the solution???

kotela it's better to post the question itself to get prompt replies. I guess you are talking about the following question:

On a scale that measures the intensity of a certain phenomenon, a reading of n+1 corresponds to an intensity that is 10 times the intensity corresponding to a reading of n. On that scale, the intensity corresponding to a reading of 8 is how many times as great as the intensity corresponding to a reading of 3?
A. 5
B. 50
C. 10^5
D. 5^10
E. 8^10 - 3^10

Basically we are given that each number on the scale is 10 times the previous number. For example:
If reading of n=3 is 5 then the reading of n=4 would be 5*10 --> the reading of n=5 would be 5*10^2 --> the reading of n=6 would be 5*10^3. Therefore the reading of 8 will be 10^5 times as great as the reading of 3 (the power of 10 goes up by 1 for each step in reading and as there are 5 steps from 3 to 8 then the reading of 8 will be 10^5 times as great as the reading of 3).

Or think about it this way: we have functional relationship: when we increase the reading by 1 the intensity increases 10 times the previous one: $$f(n+1)=10*f(n)$$.

So if $$f(3)=x$$, then $$f(4)=10*f(3)=10x$$ and so on. Therefore $$f(8)=10^5*f(3)$$.

Hope it's clear.
_________________
Senior Manager
Joined: 28 Jul 2011
Posts: 343
Location: United States
GPA: 3.86
WE: Accounting (Commercial Banking)

### Show Tags

14 Jan 2012, 06:28
Bunuel wrote:
kotela wrote:
Hey Guys i didn't understand the solution to the problem in OG 12 PS#98, can anyone please explain me the solution???

kotela it's better to post the question itself to get prompt replies. I guess you are talking about the following question:

On a scale that measures the intensity of a certain phenomenon, a reading of n+1 corresponds to an intensity that is 10 times the intensity corresponding to a reading of n. On that scale, the intensity corresponding to a reading of 8 is how many times as great as the intensity corresponding to a reading of 3?
A. 5
B. 50
C. 10^5
D. 5^10
E. 8^10 - 3^10

Basically we are given that each number on the scale is 10 times the previous number. For example:
If reading of n=3 is 5 then the reading of n=4 would be 5*10 --> the reading of n=5 would be 5*10^2 --> the reading of n=6 would be 3*10^3. Therefore the reading of 8 will be 10^5 times as great as the reading of 3 (the power of 10 goes up by 1 for each step in reading and as there are 5 steps from 3 to 8 then the reading of 8 will be 10^5 times as great as the reading of 3).

Or think about it this way: we have functional relationship: when we increase the reading by 1 the intensity increases 10 times the previous one: $$f(n+1)=10*f(n)$$.

So if $$f(3)=x$$, then $$f(4)=10*f(3)=10x$$ and so on. Therefore $$f(8)=10^5*f(3)$$.

Hope it's clear.

Thanks a lot.....I will
_________________

Intern
Joined: 12 May 2012
Posts: 19
Location: United States
Concentration: Technology, Human Resources

### Show Tags

07 Jun 2012, 01:09
gnan wrote:
As the intensity increases 10 times every time

from 3 to 8, it increases 5 times. So,answer is 10^5

thanks a lot that was very helpful
VP
Status: Far, far away!
Joined: 02 Sep 2012
Posts: 1057
Location: Italy
Concentration: Finance, Entrepreneurship
GPA: 3.8

### Show Tags

13 Mar 2013, 12:13
2
1
We know that:
$$f(n+1)=10f(n)$$

so $$f(8)=10f(7)$$ , $$f(7)=10f(6)$$ and so on...

$$f(8)=10*10*10*10*10f(3)$$

Each 10 represents a "step back"
_________________

It is beyond a doubt that all our knowledge that begins with experience.

Kant , Critique of Pure Reason

Tips and tricks: Inequalities , Mixture | Review: MGMAT workshop
Strategy: SmartGMAT v1.0 | Questions: Verbal challenge SC I-II- CR New SC set out !! , My Quant

Rules for Posting in the Verbal Forum - Rules for Posting in the Quant Forum[/size][/color][/b]

Intern
Joined: 04 Jun 2014
Posts: 2
Re: On a scale that measures the intensity of a certain phenomen  [#permalink]

### Show Tags

19 Jul 2014, 01:47
4
1
A soln. easy to understand-

For n=3, consider the intensity to be x.

For n+1 = 4 , we have [intensity*10 ]= 10x
For n+2 = 5 , we have [10x*10 ]= 100x
For n+3 = 6 , we have [100x*10 ]= 1000x
For n+4 = 7 , we have [1000x*10 ]= 10000x
For n+5 = 8 , we have [10000x*10 ]= 100000x

Now , for n = 8 -->100000x = 10^5 x
which is 10^5 times x, the original intensity at n=3
Manager
Joined: 10 Jun 2015
Posts: 118
Re: On a scale that measures the intensity of a certain phenomen  [#permalink]

### Show Tags

14 Aug 2015, 02:23
1
mydreammba wrote:
On a scale that measures the intensity of a certain phenomenon, a reading of n+1 corresponds to an intensity that is 10 times the intensity corresponding to a reading of n. On that scale, the intensity corresponding to a reading of 8 is how many times as great as the intensity corresponding to a reading of 3?

(A) 5
(B) 50
(C) 10^5
(D) 5^10
(E) 8^10 - 3^10

n = 10^(n-1)*k , where n=1,2,3,.......
8 = 10^7*k
3 = 10^2*k
It implies 8 is 10^5 times of 3
Senior Manager
Joined: 15 Oct 2015
Posts: 311
Concentration: Finance, Strategy
GPA: 3.93
WE: Account Management (Education)
Re: On a scale that measures the intensity of a certain phenomen  [#permalink]

### Show Tags

28 Feb 2016, 10:27
mydreammba wrote:
On a scale that measures the intensity of a certain phenomenon, a reading of n+1 corresponds to an intensity that is 10 times the intensity corresponding to a reading of n. On that scale, the intensity corresponding to a reading of 8 is how many times as great as the intensity corresponding to a reading of 3?

(A) 5
(B) 50
(C) 10^5
(D) 5^10
(E) 8^10 - 3^10

According to Manhattan-Gmat, the GMAT is a test of foreign language.
Target Test Prep Representative
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2827
Re: On a scale that measures the intensity of a certain phenomen  [#permalink]

### Show Tags

02 May 2016, 06:18
mydreammba wrote:
On a scale that measures the intensity of a certain phenomenon, a reading of n+1 corresponds to an intensity that is 10 times the intensity corresponding to a reading of n. On that scale, the intensity corresponding to a reading of 8 is how many times as great as the intensity corresponding to a reading of 3?

(A) 5
(B) 50
(C) 10^5
(D) 5^10
(E) 8^10 - 3^10

To solve this problem we need to examine the information in the first sentence. We are told that “a reading of n + 1 corresponds to an intensity that is 10 times the intensity corresponding to a reading of n.”

Let’s practice this idea with some real numbers. Let’s say n is 2. This means that n + 1 = 3. With the information we were given we can say that a reading of 3 is ten times as great as the intensity of a reading of 2.

Furthermore, we can say that a reading of 4 is actually 10 x 10 = 10^2 times as great as the intensity of a reading of 2.

Increasing one more unit, we can say that a reading of 5 is 10 x 10 x 10 = 10^3 times as great as the intensity of a reading of 2.

We have found a pattern, which can be applied to the problem presented in the stem:

3 is “one” unit away from 2, and thus a reading of 3 is 10^1 times as great as the intensity of a reading of 2.

4 is “two” units away from 2, and thus a reading of 4 is 10^2 times as great as the intensity of a reading of 2.

5 is “three” units away from 2, and thus a reading of 5 is 10^3 times as great as the intensity of a measure of 2.

We can use this pattern to easily answer the question. Here we are being asked for the number of times the intensity corresponding to a reading of 8 is as great as the intensity corresponding to a reading of 3. Because 8 is 5 units greater than 3, a reading of 8 is 10^5 times as great as the intensity corresponding to a reading of 3.

_________________

Jeffery Miller

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Manager
Joined: 22 May 2015
Posts: 108
Re: On a scale that measures the intensity of a certain phenomen  [#permalink]

### Show Tags

20 Mar 2017, 06:17
From question

n+1 = N * 10

say the readings are 1,10,100,1000,10^4,10^5 so on... Implies it is 5 times greater
_________________

Consistency is the Key

Director
Status: Come! Fall in Love with Learning!
Joined: 05 Jan 2017
Posts: 542
Location: India
Re: On a scale that measures the intensity of a certain phenomen  [#permalink]

### Show Tags

21 Mar 2017, 03:12
mydreammba wrote:
On a scale that measures the intensity of a certain phenomenon, a reading of n+1 corresponds to an intensity that is 10 times the intensity corresponding to a reading of n. On that scale, the intensity corresponding to a reading of 8 is how many times as great as the intensity corresponding to a reading of 3?

(A) 5
(B) 50
(C) 10^5
(D) 5^10
(E) 8^10 - 3^10

we can say that f(n) = 10^n
f(8)/ f(3) = 10^8/10^3 = 10^5
_________________

GMAT Mentors

Director
Joined: 02 Sep 2016
Posts: 670
Re: On a scale that measures the intensity of a certain phenomen  [#permalink]

### Show Tags

02 Apr 2017, 23:05
1
The intensity of 3 is n.
8-3= 5

Therefore the intensity of 8 will be 5 times the intensity of 3.
_________________

Help me make my explanation better by providing a logical feedback.

If you liked the post, HIT KUDOS !!

Don't quit.............Do it.

Manager
Joined: 30 Apr 2013
Posts: 78
Re: On a scale that measures the intensity of a certain phenomen  [#permalink]

### Show Tags

24 Aug 2017, 23:16
what level question is this?
Math Expert
Joined: 02 Sep 2009
Posts: 52906
Re: On a scale that measures the intensity of a certain phenomen  [#permalink]

### Show Tags

24 Aug 2017, 23:18
santro789 wrote:
what level question is this?

You can check difficulty level of a question along with the stats on it in the first post. For this question Difficulty: 600-700 Level.
_________________
Intern
Joined: 22 Oct 2017
Posts: 31
Re: On a scale that measures the intensity of a certain phenomen  [#permalink]

### Show Tags

02 Dec 2017, 04:42
1
Honestly this question is very confusing for me.
Based on the question stem I cannot recognize that the intensity increases 10 times every time...
EMPOWERgmat Instructor
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 13540
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: On a scale that measures the intensity of a certain phenomen  [#permalink]

### Show Tags

05 Mar 2018, 12:03
1
Hi All,

The logic behind this question is similar to how earthquakes are measured, but you don't need to recognize that to answer the question correctly. Like many questions on the Quant section, this question needs to be "played with" a bit.

We're told that with each "+1" increase in the "level of intensity" on a scale, the intensity of a phenomenon increases 10 times.

So, for example:
Level 1 = Z intensity
Level 2 = 10Z intensity
Level 3 = 100Z intensity
Level 4 = 1,000Z intensity
Etc.

We're asked how many TIMES greater "level 8" is than "level 3", so I can either continue on with the table or use "exponent math"

The table….
Level 3 = 100Z
Level 4 = 1,000Z
Level 5 = 10,00Z
Level 6 = 100,000Z
Level 7 = 1,000,000Z
Level 8 = 10,000,000Z

Level 8/Level 3 =
10,000,000Z/100Z =
10,000 times greater

Using "exponent math", we know that every level is "10x" greater than the previous level. Since Level 8 is "5 levels" above Level 3, that would be 10^5 greater.

GMAT assassins aren't born, they're made,
Rich
_________________

760+: Learn What GMAT Assassins Do to Score at the Highest Levels
Contact Rich at: Rich.C@empowergmat.com

# Rich Cohen

Co-Founder & GMAT Assassin

Special Offer: Save $75 + GMAT Club Tests Free Official GMAT Exam Packs + 70 Pt. Improvement Guarantee www.empowergmat.com/ *****Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***** Manager Joined: 30 May 2018 Posts: 83 Concentration: General Management, Marketing GMAT 1: 750 Q49 V45 GPA: 3.45 WE: Other (Retail) Re: On a scale that measures the intensity of a certain phenomen [#permalink] ### Show Tags 23 Sep 2018, 23:25 mikemcgarry wrote: abusaleh wrote: Can anyone give me proper explanation of this question? On a scale that measures the intensity of a certain phenomenon, a reading of n+1 corresponds to an intensity that is 10 times the intensity corresponding to a reading of n. On that scale, the intensity corresponding to a reading of 8 is how many times as great as the intensity corresponding to a reading of 3? A) 5 B) 50 C) 10^5 D) 5^10 E) 8^10 - 3^10 Dear abusaleh, This is a tricky question. It is based on logarithmic scales --- both the Richter scale for earthquakes and the decibel scale for the volume of sound follow this pattern. It tell us if we we go from n to n+1 on the scale, the intensity is 10 times greater. Start at 3. If we go from 3 to 4 on the scale, the intensity increases 10 times. Then from 4 to 5, it increases 10 times. Same, from 5 to 6, from 6 to 7, and from 7 to 8. There are five "steps" from 3 to 8, and each one of these steps increases the intensity by a factor of 10. That means, when we go from 3 to 8 on the scale, we multiply the intensity by 10 five times ---- 10*10*10*10*10 = 10^5 Answer = C Does this make sense? Mike Yeah , but whats the logic behind multiplying , why not add ? _________________ Kudos if you agree , Comment if you don't !!! EMPOWERgmat Instructor Status: GMAT Assassin/Co-Founder Affiliations: EMPOWERgmat Joined: 19 Dec 2014 Posts: 13540 Location: United States (CA) GMAT 1: 800 Q51 V49 GRE 1: Q170 V170 Re: On a scale that measures the intensity of a certain phenomen [#permalink] ### Show Tags 24 Sep 2018, 10:33 Hi Arpitkumar, A few posts in this thread explain how the 'math' works (including the one directly above your post) - we're told that each increase of "+1" in a 'reading' translates to a "10 TIMES" increase in intensity. Since the question asks for how many 'TIMES GREATER' one INTENSITY is than another, then we are clearly going to be using multiplication. If the question had asked for the difference one READING over another, then we would use addition. GMAT assassins aren't born, they're made, Rich _________________ 760+: Learn What GMAT Assassins Do to Score at the Highest Levels Contact Rich at: Rich.C@empowergmat.com # Rich Cohen Co-Founder & GMAT Assassin Special Offer: Save$75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/

*****Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!*****

Re: On a scale that measures the intensity of a certain phenomen   [#permalink] 24 Sep 2018, 10:33
Display posts from previous: Sort by