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

 It is currently 18 Jun 2019, 08:00 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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.  A migrating bird flew across a lake at an average speed of 18 meters p

Author Message
TAGS:

Hide Tags

Senior Manager  Joined: 12 Aug 2015
Posts: 283
Concentration: General Management, Operations
GMAT 1: 640 Q40 V37 GMAT 2: 650 Q43 V36 GMAT 3: 600 Q47 V27 GPA: 3.3
WE: Management Consulting (Consulting)
A migrating bird flew across a lake at an average speed of 18 meters p  [#permalink]

Show Tags

2
27 00:00

Difficulty:   55% (hard)

Question Stats: 68% (02:23) correct 32% (02:20) wrong based on 415 sessions

HideShow timer Statistics

A migrating bird flew across a lake at an average speed of 18 meters per second. Was the distance that the bird flew across the lake less than 21 kilometers? (1 kilometer = 1000 meters)

(1) It took the bird less than 20 minutes to fly across the lake.

(2) It took the bird less than 0.4 hour to fly across the lake.

_________________
KUDO me plenty
Math Expert V
Joined: 02 Aug 2009
Posts: 7757
Re: A migrating bird flew across a lake at an average speed of 18 meters p  [#permalink]

Show Tags

12
5
A migrating bird flew across a lake at an average speed of 18 meters per second. Was the distance that the bird flew across the lake less than 21 kilometers? (1 kilometer = 1000 meters)

(1) It took the bird less than 20 minutes to fly across the lake.

(2) It took the bird less than 0.4 hour to fly across the lake.

Hi,
the moment we are given SPEED and asked for distance, and the choices are in TIME, CHANGE speed and distance in TIME...
At a speed of 18m per sec, the bird will travel 21 kms in 21000/18 secs = 7000/6 seconds or 1167 seconds..
When can we answer the Q-
A) If the time is less than 1167 secs, we can answer the Q as definite YES
B) If the time is greater than 1167 secs, we can answer the Q as definite NO..

lets see the statements

(1) It took the bird less than 20 minutes to fly across the lake.
20 minutes is 1200 secs...
so time can be 1180 , ans is NO
and if time is 1110, ans is YES..
Insuff..

(2) It took the bird less than 0.4 hour to fly across the lake.
0.4hour = .4*60 *60 secs = 1440 secs..
we can take same example as in (1)..
again Insuff..

Combined..
the set of examples remain..
time can be 1180 , ans is NO
and if time is 1110, ans is YES..
Insuff..
E
_________________
General Discussion
Manager  S
Joined: 13 Dec 2013
Posts: 150
Location: United States (NY)
Schools: Cambridge"19 (A)
GMAT 1: 710 Q46 V41 GMAT 2: 720 Q48 V40 GPA: 4
WE: Consulting (Consulting)
Re: A migrating bird flew across a lake at an average speed of 18 meters p  [#permalink]

Show Tags

1
A migrating bird flew across a lake at an average speed of 18 meters per second. Was the distance that the bird flew across the lake less than 21 kilometers? (1 kilometer = 1000 meters)

(1) It took the bird less than 20 minutes to fly across the lake.

(2) It took the bird less than 0.4 hour to fly across the lake.

1) Distance covered in 20min = 18x60x20=21600. Therefore, distance is <21600. Insuff.
2) 0.4h = 24min, which allows for a greater distance than 1). Insuff.
1) and 2) Insuff. No new information from using both statements.
Intern  S
Joined: 26 Oct 2016
Posts: 25
Re: A migrating bird flew across a lake at an average speed of 18 meters p  [#permalink]

Show Tags

chetan2u wrote:
A migrating bird flew across a lake at an average speed of 18 meters per second. Was the distance that the bird flew across the lake less than 21 kilometers? (1 kilometer = 1000 meters)

(1) It took the bird less than 20 minutes to fly across the lake.

(2) It took the bird less than 0.4 hour to fly across the lake.

Hi,
the moment we are given SPEED and asked for distance, and the choices are in TIME, CHANGE speed and distance in TIME...
At a speed of 18m per sec, the bird will travel 21 kms in 21000/18 secs = 7000/6 seconds or 1167 seconds..
When can we answer the Q-
A) If the time is less than 1167 secs, we can answer the Q as definite YES
B) If the time is greater than 1167 secs, we can answer the Q as definite NO..

lets see the statements

(1) It took the bird less than 20 minutes to fly across the lake.
20 minutes is 1200 secs...
so time can be 1180 , ans is NO
and if time is 1110, ans is YES..
Insuff..

(2) It took the bird less than 0.4 hour to fly across the lake.
0.4hour = .4*60 *60 secs = 1440 secs..
we can take same example as in (1)..
again Insuff..

Combined..
the set of examples remain..
time can be 1180 , ans is NO
and if time is 1110, ans is YES..
Insuff..
E

Can you let me know where I went wrong:
I converted Speed into Km/h so its 64.8 Km/h
Now according to first statement t<20 mins i.e less than 1/3 hrs or 0.33 hrs

Now If I calculate the distance taking the max cvalue say 0.32 * 64.8 its 20.7 which is less than 21 hence I marked A.
Current Student S
Joined: 24 Jan 2017
Posts: 58
Re: A migrating bird flew across a lake at an average speed of 18 meters p  [#permalink]

Show Tags

ezzo wrote:
chetan2u wrote:
A migrating bird flew across a lake at an average speed of 18 meters per second. Was the distance that the bird flew across the lake less than 21 kilometers? (1 kilometer = 1000 meters)

(1) It took the bird less than 20 minutes to fly across the lake.

(2) It took the bird less than 0.4 hour to fly across the lake.

Hi,
the moment we are given SPEED and asked for distance, and the choices are in TIME, CHANGE speed and distance in TIME...
At a speed of 18m per sec, the bird will travel 21 kms in 21000/18 secs = 7000/6 seconds or 1167 seconds..
When can we answer the Q-
A) If the time is less than 1167 secs, we can answer the Q as definite YES
B) If the time is greater than 1167 secs, we can answer the Q as definite NO..

lets see the statements

(1) It took the bird less than 20 minutes to fly across the lake.
20 minutes is 1200 secs...
so time can be 1180 , ans is NO
and if time is 1110, ans is YES..
Insuff..

(2) It took the bird less than 0.4 hour to fly across the lake.
0.4hour = .4*60 *60 secs = 1440 secs..
we can take same example as in (1)..
again Insuff..

Combined..
the set of examples remain..
time can be 1180 , ans is NO
and if time is 1110, ans is YES..
Insuff..
E

Can you let me know where I went wrong:
I converted Speed into Km/h so its 64.8 Km/h
Now according to first statement t<20 mins i.e less than 1/3 hrs or 0.33 hrs

Now If I calculate the distance taking the max cvalue say 0.32 * 64.8 its 20.7 which is less than 21 hence I marked A.

Hi ezzo,
Statement 1 says that it took the bird less than 20 minutes(or 0.33hrs) to fly across the lake. The time could be 0.32 hours, or it could be 0.3299 hours.
If the time were 0.32 hours, as you have calculated, the distance is less than 21. However, if the time were 0.3299 hours, the distance is 21.38, which is more than 21km.
Current Student S
Joined: 24 Jan 2017
Posts: 58
A migrating bird flew across a lake at an average speed of 18 meters p  [#permalink]

Show Tags

1
In these kinds of questions, it is best to first calculate the required information to answer the question, and then compare this information with Statements 1 and 2.
For example, we are given:
s=18 m/s
and we want to find out if total distance is less than 21km.
d>21km or 21,000m

First, convert speed to m/min to make the information comparable to statements 1 and 2.
(18 m/s) (60 s/min) = 18*6 m/min

To calculate the time,
t> 21,000/(18*6) = (7*3*100)/(9*2*3*2) [FACTORING WILL BE EASIER THAN MULTIPLYING THEN EVENTUALLY DIVIDING)
t> 7*25/9
t>175/9
t>19.44

(1) It took the bird less than 20 minutes to fly across the lake.
t could be less than 19.44 or could be more than 19.44. INSUFFICIENT.

(2) It took the bird less than 0.4 hour to fly across the lake.
0.4 hour=24min. Again, t could be less than 19.44 or could be more than 19.44. INSUFFICIENT.

Statement b did not really bring new information as we already know from Statement 1 that t is less than 19.44.
Thus 1&2 INSUFFICIENT.
Math Expert V
Joined: 02 Aug 2009
Posts: 7757
Re: A migrating bird flew across a lake at an average speed of 18 meters p  [#permalink]

Show Tags

ezzo wrote:
chetan2u wrote:
A migrating bird flew across a lake at an average speed of 18 meters per second. Was the distance that the bird flew across the lake less than 21 kilometers? (1 kilometer = 1000 meters)

(1) It took the bird less than 20 minutes to fly across the lake.

(2) It took the bird less than 0.4 hour to fly across the lake.

Hi,
the moment we are given SPEED and asked for distance, and the choices are in TIME, CHANGE speed and distance in TIME...
At a speed of 18m per sec, the bird will travel 21 kms in 21000/18 secs = 7000/6 seconds or 1167 seconds..
When can we answer the Q-
A) If the time is less than 1167 secs, we can answer the Q as definite YES
B) If the time is greater than 1167 secs, we can answer the Q as definite NO..

lets see the statements

(1) It took the bird less than 20 minutes to fly across the lake.
20 minutes is 1200 secs...
so time can be 1180 , ans is NO
and if time is 1110, ans is YES..
Insuff..

(2) It took the bird less than 0.4 hour to fly across the lake.
0.4hour = .4*60 *60 secs = 1440 secs..
we can take same example as in (1)..
again Insuff..

Combined..
the set of examples remain..
time can be 1180 , ans is NO
and if time is 1110, ans is YES..
Insuff..
E

Can you let me know where I went wrong:
I converted Speed into Km/h so its 64.8 Km/h
Now according to first statement t<20 mins i.e less than 1/3 hrs or 0.33 hrs

Now If I calculate the distance taking the max cvalue say 0.32 * 64.8 its 20.7 which is less than 21 hence I marked A.

hi dont complicate the calculations by taking decimals..
so t<20min or t<1/3..
thus d<t*speed or d< 64.8*1/3...d<21.6
so d can be 21.5 also and 10 also..
insuff

hope it helps
_________________
Manager  G
Joined: 21 Mar 2017
Posts: 136
Location: India
GMAT 1: 560 Q48 V20 WE: Other (Computer Software)
Re: A migrating bird flew across a lake at an average speed of 18 meters p  [#permalink]

Show Tags

Bunuel Do we have a separate question directory for this type of questions? atleast one such question comes in gmat always.
_________________
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
When nothing seem to help, I would go and look at a Stonecutter hammering away at his rock perhaps a hundred time without as much as a crack showing in it.
Yet at the hundred and first blow it would split in two.
And I knew it was not that blow that did it, But all that had gone Before
.
Math Expert V
Joined: 02 Sep 2009
Posts: 55668
Re: A migrating bird flew across a lake at an average speed of 18 meters p  [#permalink]

Show Tags

Senior Manager  G
Joined: 02 Apr 2014
Posts: 474
Location: India
Schools: XLRI"20
GMAT 1: 700 Q50 V34 GPA: 3.5
A migrating bird flew across a lake at an average speed of 18 meters p  [#permalink]

Show Tags

Question: 18t < 21000
=> t < 21000/18 secs?
=> t < 7000/6 secs?
=> t < 7000/360 mins?
=> t < 19.x mins?

Statement 1: It took the bird less than 20 minutes to fly across the lake. => t < 20 mins => not suff
Statement 2: It took the bird less than 0.4 hour to fly across the lake. => t < 24 mins => not suff

combining 1 + 2, t < 20, but still insuff to answer, t < 19.x?=> (E)
Non-Human User Joined: 09 Sep 2013
Posts: 11386
Re: A migrating bird flew across a lake at an average speed of 18 meters p  [#permalink]

Show Tags

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: A migrating bird flew across a lake at an average speed of 18 meters p   [#permalink] 25 Apr 2019, 17:22
Display posts from previous: Sort by

A migrating bird flew across a lake at an average speed of 18 meters p  