It is currently 19 Oct 2017, 07:50

# STARTING SOON:

Live Chat with Cornell Adcoms in Main Chat Room  |  R1 Interview Invites: MIT Sloan Chat  |  UCLA Anderson Chat  |  Duke Fuqua Chat (EA Decisions)

### 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

# In an electric circuit, two resistors with resistances x and y are con

Author Message
TAGS:

### Hide Tags

Manager
Joined: 23 Jan 2006
Posts: 192

Kudos [?]: 36 [0], given: 0

In an electric circuit, two resistors with resistances x and y are con [#permalink]

### Show Tags

12 Apr 2006, 05:18
3
This post was
BOOKMARKED
00:00

Difficulty:

25% (medium)

Question Stats:

68% (00:48) correct 32% (00:55) wrong based on 313 sessions

### HideShow timer Statistics

In an electric circuit, two resistors with resistances x and y are connected in parallel. In this case, if r is the combined resistance of these two resistors, then the reciprocal of r is equal to the sum of the reciprocals of x and y. What is r in terms of x and y?

(A) xy
(B) x + y
(C) 1/(x + y)
(D) xy/(x + y)
(E) (x + y)/xy

OPEN DISCUSSION OF THIS QUESTION IS HERE: in-an-electric-circuit-two-resistors-with-resistances-x-and-144899.html
[Reveal] Spoiler: OA

Kudos [?]: 36 [0], given: 0

Director
Joined: 06 Feb 2006
Posts: 893

Kudos [?]: 122 [1], given: 0

Re: In an electric circuit, two resistors with resistances x and y are con [#permalink]

### Show Tags

12 Apr 2006, 05:25
1
KUDOS
I would simply concentrate on the following extract.... I think it is enough to answer the question.

....the reciprocal of r is equal to the sum of the reciprocals of x and y. What is r in terms of x and y?

Kudos [?]: 122 [1], given: 0

Senior Manager
Joined: 11 Nov 2005
Posts: 325

Kudos [?]: 15 [0], given: 0

Location: London
Re: In an electric circuit, two resistors with resistances x and y are con [#permalink]

### Show Tags

12 Apr 2006, 05:25
D.

The wordings look fine.
The Qsays that r is combined resistance of x y, and the relation of r, x, y is such that..... so find R

1/R =1/X +1/Y

1/R = (X+Y)/XY

R= XY/(X+Y)

Kudos [?]: 15 [0], given: 0

Manager
Joined: 23 Jan 2006
Posts: 192

Kudos [?]: 36 [0], given: 0

Re: In an electric circuit, two resistors with resistances x and y are con [#permalink]

### Show Tags

12 Apr 2006, 05:30
1
This post was
BOOKMARKED
SimaQ wrote:
I would simply concentrate on the following extract.... I think it is enough to answer the question.

....the reciprocal of r is equal to the sum of the reciprocals of x and y. What is r in terms of x and y?

right. (SunShine - you have the correct answer too)
But what about "r is the combined resistance of these two resistors"
Wouldn't that say r = x+y? I understand that the solution wouldn't be that simple, but I couldn't grasp how r could be the combination of the resistances, while the reciprocal of r is equal to the sum of the reciprocals of the resistances.

Kudos [?]: 36 [0], given: 0

VP
Joined: 29 Apr 2003
Posts: 1403

Kudos [?]: 30 [0], given: 0

Re: In an electric circuit, two resistors with resistances x and y are con [#permalink]

### Show Tags

12 Apr 2006, 05:44
This a simple physics formula?

Where did u get this question from? Looks like ETS started asking simple physics problem in GMAT!

I saw another problem on kinematics somewhere using the formula:

S = ut + 1/2 * a (t^2)

Kudos [?]: 30 [0], given: 0

Manager
Joined: 23 Jan 2006
Posts: 192

Kudos [?]: 36 [0], given: 0

Re: In an electric circuit, two resistors with resistances x and y are con [#permalink]

### Show Tags

12 Apr 2006, 08:20
sm176811 wrote:
This a simple physics formula?

Where did u get this question from? Looks like ETS started asking simple physics problem in GMAT!

I saw another problem on kinematics somewhere using the formula:

S = ut + 1/2 * a (t^2)

This is from the OG 11. Q230 or so i beleive.
I'm not sure this is actual physics. Even though the questing is talking about circuits, it is asking you to determine their relationship algebraically. The question could have used any domain - it is the relationship that is important

Kudos [?]: 36 [0], given: 0

VP
Joined: 29 Apr 2003
Posts: 1403

Kudos [?]: 30 [0], given: 0

Re: In an electric circuit, two resistors with resistances x and y are con [#permalink]

### Show Tags

12 Apr 2006, 08:28
No, the relationship is not important! But helps if u have the bacground.

There was a problem abt a ball being thrown up. U had to make some assumption abt heights, with wud have been obvious if u had done physics!

Let me see whether i can find that problem.

Kudos [?]: 30 [0], given: 0

Director
Joined: 06 Feb 2006
Posts: 893

Kudos [?]: 122 [0], given: 0

Re: In an electric circuit, two resistors with resistances x and y are con [#permalink]

### Show Tags

12 Apr 2006, 09:56
kook44 wrote:
SimaQ wrote:
I would simply concentrate on the following extract.... I think it is enough to answer the question.

....the reciprocal of r is equal to the sum of the reciprocals of x and y. What is r in terms of x and y?

right. (SunShine - you have the correct answer too)
But what about "r is the combined resistance of these two resistors"
Wouldn't that say r = x+y? I understand that the solution wouldn't be that simple, but I couldn't grasp how r could be the combination of the resistances, while the reciprocal of r is equal to the sum of the reciprocals of the resistances.

It does not matter. You should concentrate on the sentence that says that reciprocal of r is equal to the sum of reciprocals of x and y. It is a stated fact so we can construct a simple equation and solve it....

Kudos [?]: 122 [0], given: 0

Intern
Joined: 16 Mar 2006
Posts: 9

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

Location: USA
Re: In an electric circuit, two resistors with resistances x and y are con [#permalink]

### Show Tags

14 Apr 2006, 11:07
if r is the combined resistance of these two resistors
Here it does not mean X+Y=R, this is an electrical term saying the total resistance of the circuit is, where as its total is obtained by the reprocal statement.
_________________

"There is nothing as purifying as knowledge"

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

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 16674

Kudos [?]: 273 [0], given: 0

Re: In an electric circuit, two resistors with resistances x and y are con [#permalink]

### Show Tags

16 Nov 2014, 20:23
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 [?]: 273 [0], given: 0

Math Expert
Joined: 02 Sep 2009
Posts: 41892

Kudos [?]: 128852 [1], given: 12183

Re: In an electric circuit, two resistors with resistances x and y are con [#permalink]

### Show Tags

17 Nov 2014, 01:31
1
KUDOS
Expert's post
kook44 wrote:
In an electric circuit, two resistors with resistances x and y are connected in parallel. In this case, if r is the combined resistance of these two resistors, then the reciprocal of r is equal to the sum of the reciprocals of x and y. What is r in terms of x and y?

(A) xy
(B) x + y
(C) 1/(x + y)
(D) xy/(x + y)
(E) (x + y)/xy

The wording is a bit confusing, though basically we are told that 1/r = 1/x + 1/y, from which it follows that r=xy/(x + y).

OPEN DISCUSSION OF THIS QUESTION IS HERE: in-an-electric-circuit-two-resistors-with-resistances-x-and-144899.html
_________________

Kudos [?]: 128852 [1], given: 12183

Re: In an electric circuit, two resistors with resistances x and y are con   [#permalink] 17 Nov 2014, 01:31
Display posts from previous: Sort by