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# Today Rose is twice as old as Sam and Sam is 3 years younger

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Intern
Joined: 13 Jul 2008
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Today Rose is twice as old as Sam and Sam is 3 years younger [#permalink]

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14 Oct 2008, 18:04
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Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 3 sessions

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Today Rose is twice as old as Sam and Sam is 3 years younger than Tina. If Rose, Sam, and TIna are all alive 4 years from today, which of the following must be true on that day?

1. Rose is twice as old as Sam.
2. Sam is 3 years younger than Tina.
3. Rose is older than Tina.

Only 2

OPEN DISCUSSION OF THIS QUESTION IS HERE: https://gmatclub.com/forum/today-rose-i ... 31477.html

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SVP
Joined: 05 Jul 2006
Posts: 1750

Kudos [?]: 430 [0], given: 49

Re: Today Rose is twice as old as Sam and Sam is 3 years younger [#permalink]

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15 Oct 2008, 02:44
I encountered this problem and I swore up and down the answer was 2 & 3, but the book says it is just 2, I don't get it.

Today Rose is twice as old as Sam and Sam is 3 years younger than Tina. If Rose, Sam, and TIna are all alive 4 years from today, which of the following must be true on that day?

1. Rose is twice as old as Sam.
2. Sam is 3 years younger than Tina.
3. Rose is older than Tina.[/quote]

today

t ( tina) , t-3 ( sam) ,2(t-3) ( rose)

4 years from now

t+4 ( tina) , t+1 ( sam), 2t-2( rose)

from 1

is 2(t-1) = 2( t+1)...........no

from 2

is t+1+3 = t+4........yes

from 3

is

2t-2> t+4

ie: is t>6..........we can never know..........no

thus only 2 is possible

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Senior Manager
Joined: 04 Aug 2008
Posts: 372

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Re: Today Rose is twice as old as Sam and Sam is 3 years younger [#permalink]

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15 Oct 2008, 06:41
Rosa and Tina can be a same age
_________________

The one who flies is worthy. The one who is worthy flies. The one who doesn't fly isn't worthy

Kudos [?]: 37 [0], given: 1

Director
Joined: 27 Jun 2008
Posts: 540

Kudos [?]: 69 [1], given: 92

WE 1: Investment Banking - 6yrs
Re: Today Rose is twice as old as Sam and Sam is 3 years younger [#permalink]

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15 Oct 2008, 08:36
1
KUDOS
Substitute numbers, things become easier.

Kudos [?]: 69 [1], given: 92

Senior Manager
Joined: 12 May 2010
Posts: 289

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Location: United Kingdom
Concentration: Entrepreneurship, Technology
GMAT Date: 10-22-2011
GPA: 3
WE: Information Technology (Internet and New Media)
Re: Today Rose is twice as old as Sam and Sam is 3 years younger [#permalink]

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23 Sep 2011, 12:16
best to substitute or express in terms of 1 variable to make calculation quicker and easier and you won't have to solve lots of simultaneous equations with multiple variables.

so...

approach 1: use a table to organise the info given -->

today | + 4yrs
-------------------
R| 6 | 10
S| 3 | 7
T| 6 | 10

now you can prove/disprove each statement.

Approach 2: use a table again, but use variables instead of numbers (I prefer doing this, makes things easier and neater)

today | + 4yrs
-------------------
R| 2S | 2S + 4
S| S | S + 4
T| S+3 | (S + 3) + 4 = S + 7

1. Is 2S + 4 equal to 2(S+4)? No.
2. Is Sam 3 years younger than Tina? Yes... (S + 7) (tina's age in 4 year) - 3 = S + 4 (Sam's age in 4 years)
3. Is Rose older than Tina? Not necessarily. Answer = No. I said not necessarily because if S = 2, then in 4 years R = 12 and T = 9 ... BUT IF s = 1, then in 4 years, R = 5 and T = 8... This is kind of like a D.S. question actually if you solve using algebra...

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GMAT Club Legend
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Re: Today Rose is twice as old as Sam and Sam is 3 years younger [#permalink]

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30 Jul 2017, 20:46
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).

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Re: Today Rose is twice as old as Sam and Sam is 3 years younger [#permalink]

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30 Jul 2017, 21:10
TrillTalk wrote:
Today Rose is twice as old as Sam and Sam is 3 years younger than Tina. If Rose, Sam, and TIna are all alive 4 years from today, which of the following must be true on that day?

1. Rose is twice as old as Sam.
2. Sam is 3 years younger than Tina.
3. Rose is older than Tina.

Only 2

Notice that we are asked which of the following MUST be true not COULD be true.

Stem says that "Sam is 3 years younger than Tina" which naturally be exactly so ANY number of years from today. So, II is always true. Which means that the answer is B (II only), D (I and II only) or E (II and III only).

Analyze options I and III
I. Rose is twice as old as Sam.
III. Rose is older than Tina

Now, if today Rose is 4 years old, Sam is 2 years old and Tina is 5 years old then after 4 years Rose will be 8 years old, Sam is will be 6 years old and Tina will be 9 years old, so neither option I nor option III holds true.

OPEN DISCUSSION OF THIS QUESTION IS HERE: https://gmatclub.com/forum/today-rose-i ... 31477.html
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Kudos [?]: 128873 [0], given: 12183

Re: Today Rose is twice as old as Sam and Sam is 3 years younger   [#permalink] 30 Jul 2017, 21:10
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