It is currently 19 Sep 2017, 13:26

### 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

# Between 1980 and 1985, Pierre’s investment portfolio increas

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

### Hide Tags

Manager
Status: Never ever give up on yourself.Period.
Joined: 23 Aug 2012
Posts: 150

Kudos [?]: 378 [1], given: 35

Location: India
Concentration: Finance, Human Resources
GMAT 1: 570 Q47 V21
GMAT 2: 690 Q50 V33
GPA: 3.5
WE: Information Technology (Investment Banking)
Between 1980 and 1985, Pierre’s investment portfolio increas [#permalink]

### Show Tags

14 Jan 2013, 06:56
1
This post received
KUDOS
16
This post was
BOOKMARKED
00:00

Difficulty:

95% (hard)

Question Stats:

29% (02:17) correct 71% (02:12) wrong based on 761 sessions

### HideShow timer Statistics

Between 1980 and 1985, Pierre’s investment portfolio increased in value by x%. Between 1985 and 1990, the portfolio increased in value by y%. Since 1990, the portfolio has decreased in value by z%. If x, y, and z are all positive integers, is the portfolio currently worth more than it was in 1980?

(1) x + y > z

(2) y − x > z
[Reveal] Spoiler: OA

_________________

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

Kudos [?]: 378 [1], given: 35

Math Expert
Joined: 02 Sep 2009
Posts: 41601

Kudos [?]: 124029 [3], given: 12070

Re: Between 1980 and 1985, Pierre’s investment portfolio increas [#permalink]

### Show Tags

14 Jan 2013, 07:39
3
This post received
KUDOS
Expert's post
5
This post was
BOOKMARKED
Between 1980 and 1985, Pierre’s investment portfolio increased in value by x%. Between 1985 and 1990, the portfolio increased in value by y%. Since 1990, the portfolio has decreased in value by z%. If x, y, and z are all positive integers, is the portfolio currently worth more than it was in 1980?

Say the value of the portfolio in 1980 was $1. then: Price in 1980 = 1; Price in 1985 = $$(1+\frac{x}{100})$$; Price in 1990 = $$(1+\frac{x}{100})(1+\frac{y}{100})$$; Price in now = $$(1+\frac{x}{100})(1+\frac{y}{100})(1-\frac{z}{100})$$. Question asks whether $$1<(1+\frac{x}{100})(1+\frac{y}{100})(1-\frac{z}{100})$$. (1) x + y > z. If $$x=1$$, $$y=100$$, and $$z=1$$, then $$(1+\frac{x}{100})(1+\frac{y}{100})(1-\frac{z}{100})=1.01*2*0.99>1$$ BUT if $$x=1$$, $$y=100$$, and $$z=90$$, then $$(1+\frac{x}{100})(1+\frac{y}{100})(1-\frac{z}{100})=1.01*2*0.1<1$$. Not sufficient. (2) y − x > z. Consider the same cases. Not sufficient. (1)+(2) Consider the same cases. Not sufficient. Answer: E. _________________ Kudos [?]: 124029 [3], given: 12070 Intern Joined: 27 Mar 2013 Posts: 4 Kudos [?]: [0], given: 16 GMAT 1: 480 Q32 V23 Re: Between 1980 and 1985, Pierre’s investment portfolio increas [#permalink] ### Show Tags 01 Jun 2013, 09:33 can someone explain me the difference in reasoning between the question above and this question?: gmatclub. com/forum/the-annual-rent-collected-by-a-corporation-from-a-certain-89184.html the look similar, but the questions meant to be different: The annual rent collected by a corporation from a certain building was x percent more in 1998 than in 1997 and y percent less in 1999 than in 1998. Was the annual rent collected by the corporation from the building more in 1999 than in 1997? (1) x > y (2) xy/100 < x-y cant we make the reasoning there the same as here, r=1 and solve similiar as above? Kudos [?]: [0], given: 16 VP Status: Far, far away! Joined: 02 Sep 2012 Posts: 1122 Kudos [?]: 2292 [0], given: 219 Location: Italy Concentration: Finance, Entrepreneurship GPA: 3.8 Re: Between 1980 and 1985, Pierre’s investment portfolio increas [#permalink] ### Show Tags 01 Jun 2013, 11:20 Kyuss wrote: can someone explain me the difference in reasoning between the question above and this question?: gmatclub. com/forum/the-annual-rent-collected-by-a-corporation-from-a-certain-89184.html the look similar, but the questions meant to be different: The annual rent collected by a corporation from a certain building was x percent more in 1998 than in 1997 and y percent less in 1999 than in 1998. Was the annual rent collected by the corporation from the building more in 1999 than in 1997? (1) x > y (2) xy/100 < x-y cant we make the reasoning there the same as here, r=1 and solve similiar as above? Yes you can. But whatever value of r you pick will eventually not matter. I will go directly to the solution here, so we can write the question as: $$R(1+\frac{x}{100})(1-\frac{y}{100})>R$$, as you see now we can safely divide by R (which is positive) and obtain $$(1+\frac{x}{100})(1-\frac{y}{100})>1$$. So you can assume $$R=1$$ at the beginning if this makes your calculus easier. Hope it's clear _________________ 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] Kudos [?]: 2292 [0], given: 219 Intern Joined: 19 Apr 2012 Posts: 27 Kudos [?]: 4 [0], given: 8 Re: Between 1980 and 1985, Pierre’s investment portfolio increas [#permalink] ### Show Tags 02 Jun 2013, 05:14 My approach: Simple pick-numbers. Origin value of the investment portfolio: 100. Increase by 10% and then also by 10% = 100*1,1 = 110 110 * 1,1 = 121. Decrease by 19% ~ 20% = 1/5 = ~ 24 so the total value is below 100. Same approach for the second statement. Clearly E. Kudos [?]: 4 [0], given: 8 Intern Joined: 21 Mar 2013 Posts: 42 Kudos [?]: 152 [0], given: 56 GMAT Date: 03-20-2014 Re: Between 1980 and 1985, Pierre’s investment portfolio increas [#permalink] ### Show Tags 18 Mar 2014, 03:43 Bunuel wrote: (1) x + y > z. If $$x=1$$, $$y=100$$, and $$z=1$$, then $$(1+\frac{x}{100})(1+\frac{y}{100})(1-\frac{z}{100})=1.01*2*0.99>1$$ BUT if $$x=1$$, $$y=100$$, and $$z=90$$, then $$(1+\frac{x}{100})(1+\frac{y}{100})(1-\frac{z}{100})=1.01*2*0.1<1$$. Not sufficient. (2) y − x > z. Consider the same cases. Not sufficient. (1)+(2) Consider the same cases. Not sufficient. Bunuel: Can you please share some thought on how to come up with such numbers for plugging in. Kudos [?]: 152 [0], given: 56 Senior Manager Joined: 20 Dec 2013 Posts: 268 Kudos [?]: 106 [0], given: 29 Location: India Re: Between 1980 and 1985, Pierre’s investment portfolio increas [#permalink] ### Show Tags 30 Mar 2014, 01:00 Bunuel wrote: Between 1980 and 1985, Pierre’s investment portfolio increased in value by x%. Between 1985 and 1990, the portfolio increased in value by y%. Since 1990, the portfolio has decreased in value by z%. If x, y, and z are all positive integers, is the portfolio currently worth more than it was in 1980? Say the value of the portfolio in 1980 was$1. then:

Price in 1980 = 1;
Price in 1985 = $$(1+\frac{x}{100})$$;
Price in 1990 = $$(1+\frac{x}{100})(1+\frac{y}{100})$$;
Price in now = $$(1+\frac{x}{100})(1+\frac{y}{100})(1-\frac{z}{100})$$.

Question asks whether $$1<(1+\frac{x}{100})(1+\frac{y}{100})(1-\frac{z}{100})$$.

(1) x + y > z. If $$x=1$$, $$y=100$$, and $$z=1$$, then $$(1+\frac{x}{100})(1+\frac{y}{100})(1-\frac{z}{100})=1.01*2*0.99>1$$ BUT if $$x=1$$, $$y=100$$, and $$z=90$$, then $$(1+\frac{x}{100})(1+\frac{y}{100})(1-\frac{z}{100})=1.01*2*0.1<1$$. Not sufficient.

(2) y − x > z. Consider the same cases. Not sufficient.

(1)+(2) Consider the same cases. Not sufficient.

Answer: E.

I just want to know how you come up with these numbers,Bunuel?Is there any rule of thumb?

Kudos [?]: 106 [0], given: 29

Intern
Joined: 01 Jun 2014
Posts: 5

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

Re: Between 1980 and 1985, Pierre’s investment portfolio increas [#permalink]

### Show Tags

04 Jun 2014, 19:22
E. Pick the most extreme values of z: z = 1 and z = 100.

If z = 1, pick pretty much any large values of x and y to satisfy both statements 1 and 2, and you'll see that the portfolio has net grown.

If z = 100, then pick any large values of x and y to satisfy both statements 1 and 2, and the portfolio has become 0.

Both cases satisfy statements 1 and 2, but differ in the overall result. Therefore E.

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

Manager
Joined: 14 Apr 2014
Posts: 71

Kudos [?]: 156 [0], given: 196

Between 1980 and 1985, Pierre’s investment portfolio increas [#permalink]

### Show Tags

25 Oct 2014, 04:37
Bunuel wrote:
Between 1980 and 1985, Pierre’s investment portfolio increased in value by x%. Between 1985 and 1990, the portfolio increased in value by y%. Since 1990, the portfolio has decreased in value by z%. If x, y, and z are all positive integers, is the portfolio currently worth more than it was in 1980?

Say the value of the portfolio in 1980 was $1. then: Price in 1980 = 1; Price in 1985 = $$(1+\frac{x}{100})$$; Price in 1990 = $$(1+\frac{x}{100})(1+\frac{y}{100})$$; Price in now = $$(1+\frac{x}{100})(1+\frac{y}{100})(1-\frac{z}{100})$$. Question asks whether $$1<(1+\frac{x}{100})(1+\frac{y}{100})(1-\frac{z}{100})$$. (1) x + y > z. If $$x=1$$, $$y=100$$, and $$z=1$$, then $$(1+\frac{x}{100})(1+\frac{y}{100})(1-\frac{z}{100})=1.01*2*0.99>1$$ BUT if $$x=1$$, $$y=100$$, and $$z=90$$, then $$(1+\frac{x}{100})(1+\frac{y}{100})(1-\frac{z}{100})=1.01*2*0.1<1$$. Not sufficient. (2) y − x > z. Consider the same cases. Not sufficient. (1)+(2) Consider the same cases. Not sufficient. Answer: E. Can you please tell how did you choose these numbers ? I mean within two minutes finding these number may be little difficult. So is there are some number which I have to always take care of. Please help ! Kudos [?]: 156 [0], given: 196 Manager Joined: 22 Jan 2014 Posts: 141 Kudos [?]: 73 [0], given: 145 WE: Project Management (Computer Hardware) Re: Between 1980 and 1985, Pierre’s investment portfolio increas [#permalink] ### Show Tags 25 Oct 2014, 05:09 0 daviesj wrote: Between 1980 and 1985, Pierre’s investment portfolio increased in value by x%. Between 1985 and 1990, the portfolio increased in value by y%. Since 1990, the portfolio has decreased in value by z%. If x, y, and z are all positive integers, is the portfolio currently worth more than it was in 1980? (1) x + y > z (2) y − x > z E. The quickest way to do this ques is by plugging in values for x,y,and z 1) x+y > z Now looking at FS1 we can easily say that the portfolio value would easily be greater than that it was in 1980 (assuming x and y to be very large numbers and z to be really small) To make the value smaller, we need negative growth...for that x,y,and z should be as close as possible. let x=y=z=1 compound % growth in first 2 periods = 1+1+(1*1/100) = 2.01 compound % growth in 3rd period = 2.01 - 1 - .201 = .809 which is negative growth. so insufficient. 2) y-x > z Again positive growth can be show by assuming x and y to be large and z to be small for negative growth: x=1, y=100, and z=98 (1)+(2) --> same can be done here. _________________ Illegitimi non carborundum. Kudos [?]: 73 [0], given: 145 GMAT Club Legend Joined: 09 Sep 2013 Posts: 17563 Kudos [?]: 270 [0], given: 0 Re: Between 1980 and 1985, Pierre’s investment portfolio increas [#permalink] ### Show Tags 04 Nov 2015, 09:51 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. _________________ Kudos [?]: 270 [0], given: 0 GMAT Club Legend Joined: 09 Sep 2013 Posts: 17563 Kudos [?]: 270 [0], given: 0 Re: Between 1980 and 1985, Pierre’s investment portfolio increas [#permalink] ### Show Tags 03 Dec 2016, 03:46 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. _________________ Kudos [?]: 270 [0], given: 0 Re: Between 1980 and 1985, Pierre’s investment portfolio increas [#permalink] 03 Dec 2016, 03:46 Similar topics Replies Last post Similar Topics: 2 The only contents of a photographic portfolio are 30 photographs and 6 5 17 Apr 2017, 06:41 How many of the 40 securities in a portfolio are ... 3 10 Oct 2013, 15:41 8 Robin split a total of$24,000 between 2 investments, X and Y. If inve 12 20 Feb 2017, 02:40
4 Ann and Pierre purchased \$37 worth of French fries. 5 27 Oct 2016, 12:48
3 Jessica has a limited investment portfolio of stocks and bon 7 03 Jun 2013, 02:21
Display posts from previous: Sort by

# Between 1980 and 1985, Pierre’s investment portfolio increas

 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®.