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

 It is currently 21 Jan 2019, 05:51

### 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 January
PrevNext
SuMoTuWeThFrSa
303112345
6789101112
13141516171819
20212223242526
272829303112
Open Detailed Calendar
• ### GMAT Club Tests are Free & Open for Martin Luther King Jr.'s Birthday!

January 21, 2019

January 21, 2019

10:00 PM PST

11:00 PM PST

Mark your calendars - All GMAT Club Tests are free and open January 21st for celebrate Martin Luther King Jr.'s Birthday.
• ### The winners of the GMAT game show

January 22, 2019

January 22, 2019

10:00 PM PST

11:00 PM PST

In case you didn’t notice, we recently held the 1st ever GMAT game show and it was awesome! See who won a full GMAT course, and register to the next one.

# In the figure above, what is the value of b? (1) a+c+d=225

Author Message
Director
Joined: 02 Mar 2006
Posts: 534
Location: France
In the figure above, what is the value of b? (1) a+c+d=225  [#permalink]

### Show Tags

24 Apr 2006, 11:43
1
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 8 sessions

### HideShow timer Statistics

In the figure above, what is the value of b?

(1) a+c+d=225
(2) d-a =55

--== Message from the GMAT Club Team ==--

THERE IS LIKELY A BETTER DISCUSSION OF THIS EXACT QUESTION.
This discussion does not meet community quality standards. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.

Attachments

triangle.JPG [ 4.29 KiB | Viewed 1788 times ]

Manager
Joined: 13 Dec 2005
Posts: 219
Location: Milwaukee,WI

### Show Tags

24 Apr 2006, 11:54
should be B

from figure a +b+c =180
==> a +b =180 -c
a +b =d
so b= d-a

from (2) b =d-a = 55 so B is sufficient

From (1) you get a = 225- 180 = 45 , we dont know anything about d so insufficient
Manager
Joined: 20 Nov 2004
Posts: 108

### Show Tags

24 Apr 2006, 11:56
From (1), we get:

a + c + d = 225
c + d = 180

So a = 45. Not sufficient.

From (2), we get:

d - a = 55
d = 55 + a
180 - c = 55 + a
a + 55 + c = 180

So b = 55 and therefore B.

Good question. I almost fell into the trap.
Director
Joined: 02 Mar 2006
Posts: 534
Location: France

### Show Tags

24 Apr 2006, 23:51
Great! you're both right!

First, given the figure, how could we know that a c d is on a lign? I thought if that information is not given, we cannot suppose it. Tha's why I answered (E). The information give is just that a c b is a triangle...

Second point, I've learn in different GMAT DS tips, that for variables to be solved, there needs to be at least as much as equations as unknown. It doesn't seem to work if we consider following

So with (1) we have:
a+b+c=180
c+d =180
a + c + d = 225

4 variables and 3 equations are not enough to solve it => right

with (2)
a+b+c=180
c+d =180
a-d=55

It 's the same, we have 4 variables and 3 equations => false

why can't we say it isn't enough to solve it. Where's the flaw?
GMAT Club Legend
Joined: 07 Jul 2004
Posts: 4803
Location: Singapore

### Show Tags

25 Apr 2006, 00:50
karlfurt wrote:
Great! you're both right!

First, given the figure, how could we know that a c d is on a lign? I thought if that information is not given, we cannot suppose it. Tha's why I answered (E). The information give is just that a c b is a triangle...

Second point, I've learn in different GMAT DS tips, that for variables to be solved, there needs to be at least as much as equations as unknown. It doesn't seem to work if we consider following

So with (1) we have:
a+b+c=180
c+d =180
a + c + d = 225

4 variables and 3 equations are not enough to solve it => right

with (2)
a+b+c=180
c+d =180
a-d=55

It 's the same, we have 4 variables and 3 equations => false

why can't we say it isn't enough to solve it. Where's the flaw?

First, given the figure, how could we know that a c d is on a lign? I thought if that information is not given, we cannot suppose it. Tha's why I answered (E). The information give is just that a c b is a triangle...

- I think you can assume a line is straight if it's drawn straight. I can't recall the exact things you cannot assume in geometry as it's been a long time since I touched geometry. But I think the OG has a list of those items you can safely assume

Second point, I've learn in different GMAT DS tips, that for variables to be solved, there needs to be at least as much as equations as unknown. It doesn't seem to work if we consider following

- You're wrong on this one. In fact, for DS, having x number of variables does not mean you need x number of equations.

Anyway, for St1:
we know c+d = 180, and so a = 45. However, we can't solve for b as we do not know c and we can't manipulate the variables to fit into the sum of angles for a triangle.

The most we can get via manipulation is

a+b+c = 180
45+b+180-d = 180
b-d = -45 --> We still have two variables left.

However, with St 2:

You can easily write
d = a+55
So c = 180-a-55 = 125-a

a+b+c = 180
a+b+125-a = 180
b = 55
VP
Joined: 29 Apr 2003
Posts: 1371

### Show Tags

25 Apr 2006, 02:46

Whats the OA?
Senior Manager
Joined: 08 Jun 2004
Posts: 473
Location: Europe

### Show Tags

25 Apr 2006, 09:24
Definitely 'B'.
Nice question.
Director
Joined: 02 Mar 2006
Posts: 534
Location: France

### Show Tags

25 Apr 2006, 12:45
OA is B.

Concerning the solving of the equations (1) and (2), I totally understand and agree. But I was looking for a "shortcut" to answer such questions more quickly. If I knew after few seconds that in any DS involving equations that there have less or as much equations as variables, I could straight give an answer that we have( or not) enough information too answer.

So what should one think about such a statement taken out of Kaplan, in light of this DS triangle problem.

"Remember this matematical principle.Whatever number of different variables you need to solve for, you will need that same number of different equations relating at least one of those variables.

There are usually a few tough DS problems that can be made easy by applying this principle and the Kaplan Method for DS word problem. If you get such a problem, ask yoursel,' how many variables do I need to solve for? How many equations do I have?'"
Non-Human User
Joined: 09 Sep 2013
Posts: 9459
Re: In the figure above, what is the value of b? (1) a+c+d=225  [#permalink]

### Show Tags

12 Dec 2017, 18:31
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.

--== Message from the GMAT Club Team ==--

THERE IS LIKELY A BETTER DISCUSSION OF THIS EXACT QUESTION.
This discussion does not meet community quality standards. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.

_________________
Re: In the figure above, what is the value of b? (1) a+c+d=225 &nbs [#permalink] 12 Dec 2017, 18:31
Display posts from previous: Sort by