It is currently 18 Feb 2018, 22:12

### 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

# (1/11)+(1/12)+……+(1/19)+(1/20) is including in which of the following

Author Message
TAGS:

### Hide Tags

Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 4879
GPA: 3.82
(1/11)+(1/12)+……+(1/19)+(1/20) is including in which of the following [#permalink]

### Show Tags

30 Aug 2017, 00:28
1
KUDOS
Expert's post
3
This post was
BOOKMARKED
00:00

Difficulty:

55% (hard)

Question Stats:

59% (01:13) correct 41% (01:24) wrong based on 97 sessions

### HideShow timer Statistics

(1/11)+(1/12)+……+(1/19)+(1/20) is including in which of
the following ranges?

A. 0 ~ (1/5)
B. (1/5) ~ (1/4)
C. (1/4)~(1/3)
D. (1/3)~(1/2)
E. (1/2)~1
[Reveal] Spoiler: OA

_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself

Math Expert
Joined: 02 Aug 2009
Posts: 5649
Re: (1/11)+(1/12)+……+(1/19)+(1/20) is including in which of the following [#permalink]

### Show Tags

30 Aug 2017, 01:46
2
KUDOS
Expert's post
1
This post was
BOOKMARKED
MathRevolution wrote:
(1/11)+(1/12)+……+(1/19)+(1/20) is including in which of
the following ranges?

A. 0 ~ (1/5)
B. (1/5) ~ (1/4)
C. (1/4)~(1/3)
D. (1/3)~(1/2)
E. (1/2)~1

Hi..
You don't have to start Adding..
Just find the ATLEAST value..
Here the SUM has to be GREATER than 10 times lowest value= 10*1/20=1/2
So sum >1/2

Only E fits in..
E
_________________

Absolute modulus :http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html

BANGALORE/-

BSchool Forum Moderator
Joined: 26 Feb 2016
Posts: 2042
Location: India
GPA: 3.12
(1/11)+(1/12)+……+(1/19)+(1/20) is including in which of the following [#permalink]

### Show Tags

30 Aug 2017, 02:12
Expression that we need to find the range is $${(\frac{1}{11})+(\frac{1}{12})+……+(\frac{1}{19})+(\frac{1}{20})}$$

The minimum range of that expression is $$\frac{1}{20}+\frac{1}{20}$$... total 10 times
Therefore the value of that minimum expression is greater than $$\frac{10}{20}$$ or $$\frac{1}{2}$$

Similarly the range for maximum value is $$\frac{10}{11} = 0.91$$(approximately)

Hence the range for the expression must be $$\frac{1}{2}$$ < expression < 1(Option E)
_________________

Stay hungry, Stay foolish

Manager
Joined: 14 Sep 2016
Posts: 148
Re: (1/11)+(1/12)+……+(1/19)+(1/20) is including in which of the following [#permalink]

### Show Tags

30 Aug 2017, 04:51
pushpitkc wrote:
Expression that we need to find the range is $${(\frac{1}{11})+(\frac{1}{12})+……+(\frac{1}{19})+(\frac{1}{20})}$$

The minimum range of that expression is $$\frac{1}{20}+\frac{1}{20}$$... total 10 times
Therefore the value of that minimum expression is greater than $$\frac{10}{20}$$ or $$\frac{1}{2}$$

Similarly the range for maximum value is $$\frac{10}{11} = 0.91$$(approximately)

Hence the range for the expression must be $$\frac{1}{2}$$ < expression < 1(Option E)

Hi,

How are you deriving the minimum range as 1/20+1/20... ?
BSchool Forum Moderator
Joined: 26 Feb 2016
Posts: 2042
Location: India
GPA: 3.12
Re: (1/11)+(1/12)+……+(1/19)+(1/20) is including in which of the following [#permalink]

### Show Tags

30 Aug 2017, 05:17
kunalsinghNS wrote:

Hi,

How are you deriving the minimum range as 1/20+1/20... ?

We have a total of 10 elements in the expression.
The minimum range can be got by adding the smallest number
10 times.

Since 1/20 is the smallest number in the expression,
adding the number to the itself 10 times will give you the
smallest number possible(1/20 = 0.05)
When added 10 times to itself, 0.05*10 = 0.5 = 1/2!

Hope that helps!
_________________

Stay hungry, Stay foolish

Manager
Joined: 14 Sep 2016
Posts: 148
Re: (1/11)+(1/12)+……+(1/19)+(1/20) is including in which of the following [#permalink]

### Show Tags

30 Aug 2017, 21:22
Thank you for your response !
Intern
Joined: 26 Aug 2017
Posts: 5
Re: (1/11)+(1/12)+……+(1/19)+(1/20) is including in which of the following [#permalink]

### Show Tags

30 Aug 2017, 21:43
This explained method is not bad ..we can extract result from by multiply 10/20 for higher range and 10/11 for lower range...but it is a tricky solution

Sent from my Redmi 4A using GMAT Club Forum mobile app
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 4879
GPA: 3.82
Re: (1/11)+(1/12)+……+(1/19)+(1/20) is including in which of the following [#permalink]

### Show Tags

01 Sep 2017, 09:05
=> (1/20) < (1/11), (1/20) < (1/12), …, (1/20) < (1/19).
(1/20) + (1/20) + … + (1/20) < (1/11)+(1/12)+……+(1/19)+(1/20)
(1/20)*10 < (1/11)+(1/12)+……+(1/19)+(1/20)
(1/2) < (1/11)+(1/12)+……+(1/19)+(1/20)

(1/11) < (1/10), (1/12) < (1/10), … , (1/20) < (1/10)
(1/11)+(1/12)+……+(1/19)+(1/20) < (1/10) + (1/10) + … + (1/10) = 1

Thus, 1/2 < (1/11)+(1/12)+……+(1/19)+(1/20) < 1

Ans: E
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself

Re: (1/11)+(1/12)+……+(1/19)+(1/20) is including in which of the following   [#permalink] 01 Sep 2017, 09:05
Display posts from previous: Sort by