Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 29 Aug 2016, 21:30

### 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

# The speeds of three asteroids were compared. Asteroids X-13

Author Message
TAGS:

### Hide Tags

Manager
Joined: 10 Sep 2012
Posts: 150
Followers: 2

Kudos [?]: 139 [1] , given: 17

The speeds of three asteroids were compared. Asteroids X-13 [#permalink]

### Show Tags

31 Oct 2012, 17:04
1
KUDOS
11
This post was
BOOKMARKED
00:00

Difficulty:

55% (hard)

Question Stats:

70% (03:43) correct 30% (02:54) wrong based on 176 sessions

### HideShow timer Statistics

The speeds of three asteroids were compared. Asteroids X-13 and Y-14 were observed for identical durations, while asteroid Z-15 was observed for 2 seconds longer. During its period of observation, asteroid Y-14 traveled three times the distance X-13 traveled, and therefore Y-14 was found to be faster than X-13 by 2000 kilometers per second. Asteroid Z-15 had an identical speed as that of X-13, but because Z-15 was observed for a longer period, it traveled five times the distance X-13 traveled during X-13's inspection. Asteroid X-13 traveled how many kilometers during its observation?

A. 500
B. 1,600/3
C. 1,000
D. 1,500
E. 2,500

I have the solution and will paste if anyone would like it, but I'm not convinced that that this is doable in under 2 minutes.... if so, what did you guys do?
[Reveal] Spoiler: OA

Last edited by Bunuel on 01 Nov 2012, 06:07, edited 1 time in total.
Edited the question.
Director
Status: Done with formalities.. and back..
Joined: 15 Sep 2012
Posts: 647
Location: India
Concentration: Strategy, General Management
Schools: Olin - Wash U - Class of 2015
WE: Information Technology (Computer Software)
Followers: 43

Kudos [?]: 508 [1] , given: 23

Re: The speeds of three asteroids were compared. Asteroids X-13 [#permalink]

### Show Tags

31 Oct 2012, 19:08
1
KUDOS
anon1 wrote:
The speeds of three asteroids were compared. Asteroids X-13 and Y-14 were observed for identical durations, while asteroid Z-15 was observed for 2 seconds longer. During its period of observation, asteroid Y-14 traveled three times the distance X-13 traveled, and therefore Y-14 was found to be faster than X-13 by 2000 kilometers per second. Asteroid Z-15 had an identical speed as that of X-13, but because Z-15 was observed for a longer period, it traveled five times the distance X-13 traveled during X-13's inspection. Astroid X-13 traveled how many kilometers during its observation?

500
1,600/3
1,000
1,500
2,500

I have the solution and will paste if anyone would like it, but I'm not convinced that that this is doable in under 2 minutes.... if so, what did you guys do?

Ans A. Doable in 2 mins.
_________________

Lets Kudos!!!
Black Friday Debrief

Manager
Joined: 10 Sep 2012
Posts: 150
Followers: 2

Kudos [?]: 139 [1] , given: 17

Re: The speeds of three asteroids were compared. Asteroids X-13 [#permalink]

### Show Tags

31 Oct 2012, 19:29
1
KUDOS
Quote:
Ans A. Doable in 2 mins.

How did you do it?

For this problem, for me, it takes roughly a minute for me just to set up the table and go through my head what the heck is going on before I even start writing down one calculation...
Moderator
Joined: 02 Jul 2012
Posts: 1230
Location: India
Concentration: Strategy
GMAT 1: 740 Q49 V42
GPA: 3.8
WE: Engineering (Energy and Utilities)
Followers: 110

Kudos [?]: 1255 [1] , given: 116

Re: The speeds of three asteroids were compared. Asteroids X-13 [#permalink]

### Show Tags

31 Oct 2012, 21:46
1
KUDOS
1
This post was
BOOKMARKED
anon1 wrote:
Quote:
Ans A. Doable in 2 mins.

How did you do it?

For this problem, for me, it takes roughly a minute for me just to set up the table and go through my head what the heck is going on before I even start writing down one calculation...

Let distances be $$D_x, D_y, D_z$$ and time X was observed be $$t$$

Velocities are $$\frac{D_x}{t}, \frac{D_y}{t}, \frac{D_z}{t+2}$$

$$D_y = 3D_x$$

$$D_z = 5D_x$$

$$\frac{D_y}{t} = \frac{D_x}{t} + 2000$$

$$\frac{D_x}{t} = \frac{D_z}{t+2}$$

Although it took me a good 5 mins typing and formatting all this, I think setting up these equations would not take more than a min and another half for solving. At worst must be doable within 2 mins.

Kudos Please... If my post helped.
_________________

Did you find this post helpful?... Please let me know through the Kudos button.

Thanks To The Almighty - My GMAT Debrief

GMAT Reading Comprehension: 7 Most Common Passage Types

Manager
Joined: 23 Oct 2012
Posts: 57
Followers: 2

Kudos [?]: 45 [0], given: 285

Re: The speeds of three asteroids were compared. Asteroids X-13 [#permalink]

### Show Tags

03 Nov 2012, 23:16
Somebody please explain this to me ?
_________________

Director
Status: Done with formalities.. and back..
Joined: 15 Sep 2012
Posts: 647
Location: India
Concentration: Strategy, General Management
Schools: Olin - Wash U - Class of 2015
WE: Information Technology (Computer Software)
Followers: 43

Kudos [?]: 508 [4] , given: 23

Re: The speeds of three asteroids were compared. Asteroids X-13 [#permalink]

### Show Tags

03 Nov 2012, 23:30
4
KUDOS
2013gmat wrote:
Somebody please explain this to me ?

Without getting into too much maths, lets solve this.
Lets call these asteroids X,Y,Z instead of X-13/14/15 etc for simplicity.

What is given in question:
1. Notice, Z was observed 2 extra seconds - or that mean Z travelled for 2 extra seconds than X and Y.
2. Distance Y traveled was 3 times X , in same duration. This would mean speed of Y is 3 times that of X. and difference is given as 2000.
Thus, Y traveled 3 times faster (say speed =3V) than X (say speed =V) and difference is 2000 => 3V-V =2000
Or V =1000.
3. Distance Z traveled was 5 times what X traveled despite having same speed.
Z traveled 5 times what X traveled despite having same speed because Z traveled 2 exta seconds. That means, extra 2 seconds = extra 4 times distance
=> original duration of travel for X (and for Y) = 0.5 seconds

So question has become, how much X traveled in 0.5 seconds with speed 1000 km/s.
So total distance covered by X = 1000* 0.5 = 500

Ans A it is.

Hope it is clear.
_________________

Lets Kudos!!!
Black Friday Debrief

Intern
Joined: 17 May 2013
Posts: 49
GMAT Date: 10-23-2013
Followers: 0

Kudos [?]: 8 [0], given: 8

Re: The speeds of three asteroids were compared. Asteroids X-13 [#permalink]

### Show Tags

05 Aug 2013, 19:10
1
This post was
BOOKMARKED
Assume X-13 ==> X, Y -14 ==> Y and Z-15 ==> Z

Formula D =ST

Given

1. Distance traveled by Z = 5 (Distance traveled by X)
2. time of X be T, given that time of Z is T + 2
3. Speed of X and Z are the same say S

S(T+2) = 5(S x T) solving we get T = 0.5 ------ (1)

Also Given that Y traveled 3 time than X in the same time period

Difference in Speed of X and Y is 2000 and speed would be 3S - S = 2000 ==> S = 1000 ------ (2)

Distance X traveled using 1 and 2
D = ST
D = 1000 x 0.5
D = 500

Option A

Hope the thought process is right..
Took some time to get the equations....
Senior Manager
Joined: 13 May 2013
Posts: 472
Followers: 3

Kudos [?]: 139 [0], given: 134

Re: The speeds of three asteroids were compared. Asteroids X-13 [#permalink]

### Show Tags

07 Aug 2013, 10:17
The speeds of three asteroids were compared. Asteroids X-13 and Y-14 were observed for identical durations, while asteroid Z-15 was observed for 2 seconds longer. During its period of observation, asteroid Y-14 traveled three times the distance X-13 traveled, and therefore Y-14 was found to be faster than X-13 by 2000 kilometers per second. Asteroid Z-15 had an identical speed as that of X-13, but because Z-15 was observed for a longer period, it traveled five times the distance X-13 traveled during X-13's inspection. Asteroid X-13 traveled how many kilometers during its observation?

X13: (t, d, s)
Y14: (t, 3d, s+2000mi/hour)
Z15: (t+2 seconds, s, 5d)

d=?

Distance = Speed*Time
x13: d = s*t
x14: 3d = (s+2000)*t ===> 3d = ts+2000t
z15: 5d = s*(t+2t) ===> 5d = st+2st ===> 5d - 2st = st

3d = 5d - 2st + 2000t
-2d = -2st + 2000t
2d = 2st - 2000t
d = st - 1000t

x13: d = s*t
st - 1000t = s*t
s - 1000 = s
-500 = s

I got to this point and couldn't go any further. This seems like a problem where I can set up individual d=r*t formulas and solve but it appears that's not the case. For future reference how would I know not to waste my time setting up this problem in the aforementioned way? Thanks!!!

The distance of Z15 is equal to five times the distance of X13 (we established that x13 is the baseline and thus, it's measurements are d, s, t)

S(T+2) = 5(S*T) What clues would I have to know to set up the equation in this fashion? Is it because I am better off setting two identical distances together?
ST+2S = 5ST
T+2 = 5T
2=4T
t= 1/2

We are looking for distance (d=s*t) so we need to solve for speed now that we have time.
Speed y14 - speed x13
Speed = d/t
3d/t - d/t = 2000 (remember, t is the same because both asteroids were observed for the same amount of time)
2d = 2000
2 = 1000

d=s*t
d=1000*(1/2)
d=500

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 11133
Followers: 511

Kudos [?]: 134 [0], given: 0

Re: The speeds of three asteroids were compared. Asteroids X-13 [#permalink]

### Show Tags

27 Aug 2014, 08:26
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.
_________________
Current Student
Joined: 02 Apr 2012
Posts: 76
Location: United States (VA)
Concentration: Entrepreneurship, Finance
GMAT 1: 680 Q49 V34
WE: Consulting (Consulting)
Followers: 1

Kudos [?]: 46 [1] , given: 155

Re: The speeds of three asteroids were compared. Asteroids X-13 [#permalink]

### Show Tags

02 Dec 2014, 06:35
1
KUDOS
The first time I solved, I used equations. Bad decision. It took 5 mins. But I think that this approach can help us to solve it in 2 or 3 mins.

First: the question asks for the Distance (D) that X traveled. Only look for infornation to solve this.

Second: info.

Asteroids X-13 and Y-14 were observed for identical durations, and:
1) asteroid Y-14 traveled three times the distance X-13 traveled.
2) Y-14 was found to be faster than X-13 by 2000 kilometers per second
Therefore:

r+2000 (rate of speed of Y, per second) = 3r (distance traveled by Y, in one second, remember that both X and Y were observed for indentical durations) --> r= 1000

Third:
Asteroid Z had an identical speed as that of X, but because Z was observed for 2 seconds longer, it traveled five times the distance X traveled during X's inspection.

Therefore, D (distance of X) +2000 (because r=1000, Z in 2 seconds travel 2000) = 5D --> D = 500

Hope it is clear.
_________________

Encourage cooperation! If this post was very useful, kudos are welcome
"It is our attitude at the beginning of a difficult task which, more than anything else, will affect It's successful outcome" William James

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 11133
Followers: 511

Kudos [?]: 134 [0], given: 0

Re: The speeds of three asteroids were compared. Asteroids X-13 [#permalink]

### Show Tags

08 May 2016, 05:09
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.
_________________
Re: The speeds of three asteroids were compared. Asteroids X-13   [#permalink] 08 May 2016, 05:09
Similar topics Replies Last post
Similar
Topics:
Car A travels at three times the average speed of car B. Car A started 5 13 Jul 2016, 01:59
2 Three students were given three tests, the results of the first two te 3 10 Jul 2015, 02:39
Three students were given three tests, the results of the first two te 4 26 Dec 2014, 08:46
4 Roberto has three children: two girls and a boy. All were born on the 6 03 Nov 2014, 09:42
5 Three houses of the same type were advertised to be let in a 7 19 May 2014, 04:07
Display posts from previous: Sort by