It is currently 20 Nov 2017, 23:47

### 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
Your Progress

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

# What is the value of s?

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

### Hide Tags

Intern
Joined: 24 Aug 2017
Posts: 8

Kudos [?]: 5 [0], given: 1

What is the value of s? [#permalink]

### Show Tags

11 Oct 2017, 22:01
00:00

Difficulty:

45% (medium)

Question Stats:

69% (00:59) correct 31% (01:09) wrong based on 35 sessions

### HideShow timer Statistics

What is the value of s?

1) $$\frac{1}{s} = \frac{1}{(s+25)} + \frac{1}{(s+1)}$$
2) -1/5 is not a reciprocal of s
[Reveal] Spoiler: OA

Kudos [?]: 5 [0], given: 1

Math Expert
Joined: 02 Aug 2009
Posts: 5214

Kudos [?]: 5860 [1], given: 117

Re: What is the value of s? [#permalink]

### Show Tags

12 Oct 2017, 01:24
1
This post received
KUDOS
Expert's post
khalid228 wrote:
What is the value of s?

1) $$\frac{1}{s} = \frac{1}{(s+25)} + \frac{1}{(s+1)}$$
2) -1/5 is not a reciprocal of s

Let's see the statements
1) $$\frac{1}{s} = \frac{1}{(s+25)} + \frac{1}{(s+1)}$$
$$\frac{1}{s+25}+\frac{1}{s+1}-\frac{1}{s}=0........\frac{s^2+s+s^2+25s-(s^2+26s+25)}{s(s+1)(s+25)}=0.........$$
For the fraction to be 0, numerator has to be 0..
So $$s^2-25=0$$ or s=5 or s=-5
Two values possible..
Insufficient

2) -1/5 is not a reciprocal of s
s can be any value except-5
Insufficient

Combined..
Only value possible is s as 5
Sufficient

C
_________________

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

Kudos [?]: 5860 [1], given: 117

Intern
Joined: 24 Aug 2017
Posts: 8

Kudos [?]: 5 [0], given: 1

What is the value of s? [#permalink]

### Show Tags

12 Oct 2017, 01:39
chetan2u I understand the concept and ideal behind it now, but could you explain to me how you went from the first equation to the second?

$$\frac{1}{s+25}+\frac{1}{s+1}-\frac{1}{s}=0............. \frac{s^2+s+s^2+25s-(s^2+26s+25)}{s(s+1)(s+25)}=0$$

Kudos [?]: 5 [0], given: 1

Math Expert
Joined: 02 Aug 2009
Posts: 5214

Kudos [?]: 5860 [0], given: 117

What is the value of s? [#permalink]

### Show Tags

12 Oct 2017, 20:18
khalid228 wrote:
chetan2u I understand the concept and ideal behind it now, but could you explain to me how you went from the first equation to the second?

$$\frac{1}{s+25}+\frac{1}{s+1}-\frac{1}{s}=0............. \frac{s^2+s+s^2+25s-(s^2+26s+25)}{s(s+1)(s+25)}=0$$

Hi..

We are actually getting all terms in equivalent form by getting the denominator same for all fractions
First take LCM of the denominator and then simplify the term by adding all fractions.

$$\frac{1}{s+25}+\frac{1}{s+1}-\frac{1}{s}=\frac{1*(s+1)*s+(s+25)*s-(s+1)(s+25)}{(s+1)(s+25)(s)}=0............. \frac{s^2+s+s^2+25s-(s^2+26s+25)}{s(s+1)(s+25)}=0$$[/quote]
_________________

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

Kudos [?]: 5860 [0], given: 117

Director
Joined: 17 Dec 2012
Posts: 623

Kudos [?]: 535 [0], given: 16

Location: India
Re: What is the value of s? [#permalink]

### Show Tags

14 Oct 2017, 21:57
The second statement is a giveaway. It suggests we get two values from statement 1. Solving the first statement is also straightforward. We get 2 values for s. With statements 1 and 2, the question can be answered.

Hence C.
_________________

Srinivasan Vaidyaraman
Sravna
http://www.sravnatestprep.com/regularcourse.php

Premium Material
Standardized Approaches

Kudos [?]: 535 [0], given: 16

Re: What is the value of s?   [#permalink] 14 Oct 2017, 21:57
Display posts from previous: Sort by

# What is the value of s?

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.