Two missiles are launched simultaneously. Missile 1 launches : DS Archive
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 16 Jan 2017, 07:41

### 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

# Two missiles are launched simultaneously. Missile 1 launches

Author Message
Director
Joined: 22 Aug 2007
Posts: 567
Followers: 1

Kudos [?]: 50 [0], given: 0

Two missiles are launched simultaneously. Missile 1 launches [#permalink]

### Show Tags

22 Oct 2007, 19:44
00:00

Difficulty:

(N/A)

Question Stats:

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

### HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

Two missiles are launched simultaneously. Missile 1 launches at a speed of x miles per hour, increasing its speed by a factor of sqrt(x) every 10 minutes (so that after 10 minutes its speed is x*sqrt(x) , after 20 minutes its speed is x*sqrt(x)*x*sqrt(x) , and so forth. Missile 2 launches at a speed of y miles per hour, doubling its speed every 10 minutes. After 1 hour, is the speed of Missile 1 greater than that of Missile 2?

1) x=srt(y)
2) x>8

will post OA later.
VP
Joined: 10 Jun 2007
Posts: 1459
Followers: 7

Kudos [?]: 255 [0], given: 0

### Show Tags

23 Oct 2007, 05:42
IrinaOK wrote:
Two missiles are launched simultaneously. Missile 1 launches at a speed of x miles per hour, increasing its speed by a factor of sqrt(x) every 10 minutes (so that after 10 minutes its speed is x*sqrt(x) , after 20 minutes its speed is x*sqrt(x)*x*sqrt(x) , and so forth. Missile 2 launches at a speed of y miles per hour, doubling its speed every 10 minutes. After 1 hour, is the speed of Missile 1 greater than that of Missile 2?

1) x=srt(y)
2) x>8

will post OA later.

C.

After one hour...
Missile 1 will be at x^4
Missile 2 will be at y^7

(1) if x=sqrt(y), then x^4 = y^2
So the question becomes: Is y^2 > y^7
Cannot be determined because we don't know if y<1 or y>1
INSUFFICIENT

(2) don't know anything about y
INSUFFICIENT

Together, you know that x>8
This means y = x^2 and since y is greater than 1, the question becomes:
Is y > y^5
Plug in some values of y...
SUFFICIENT
Intern
Joined: 09 Oct 2007
Posts: 17
Followers: 0

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

### Show Tags

23 Oct 2007, 06:32
IrinaOK wrote:
Two missiles are launched simultaneously. Missile 1 launches at a speed of x miles per hour, increasing its speed by a factor of sqrt(x) every 10 minutes (so that after 10 minutes its speed is x*sqrt(x) , after 20 minutes its speed is x*sqrt(x)*x*sqrt(x) , and so forth. Missile 2 launches at a speed of y miles per hour, doubling its speed every 10 minutes. After 1 hour, is the speed of Missile 1 greater than that of Missile 2?

1) x=srt(y)
2) x>8

will post OA later.

M1 in 1 hour: x*root(x) (10 min) *root(x) (20 min) *root(x) (30 min) *root(x) (40 min) *root(x) (50 min) *root(x) (1 hour).

Therefore, M1 will have speed = x*x*x*x = x^4.

M2 in 1 hour: y*2 (10 min) *2 (20 min) *2(30 min) *2(40 min) *2(50 min) *2 (1 hour) = y*2*2*2*2*2*2 = 64y.

We need to compare x^4 and 64 y.

1. x = root(y), x^4 = y^2.
y^2 and 32y. If y = 1, we have 1 and 32.
If y = 100, we have 10000 and 3200.
NOT Suff.

2. x>8. Let it be 9,
9^4 and 32y - Not suff.

3. Together.

y^2 and 32y, since x>8 and x = root (y), minimum y>64.

64^2 and 32*64.

Suff.

C.
Director
Joined: 22 Aug 2007
Posts: 567
Followers: 1

Kudos [?]: 50 [0], given: 0

### Show Tags

23 Oct 2007, 10:45
forgot x and y could be less than 1...

AO is C.

Thank you, guys!
Re: DS_missiles launched   [#permalink] 23 Oct 2007, 10:45
Display posts from previous: Sort by