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M06-03

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M06-03 [#permalink]

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The first flight out of Phoenix airport had a late departure. If the next three flights departed on-time, how many subsequent flights need to depart from Phoenix on-time, for the airport's on-time departure rate to be higher than 90%?

A. 6
B. 7
C. 9
D. 10
E. 11
[Reveal] Spoiler: OA

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Re M06-03 [#permalink]

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New post 15 Sep 2014, 23:26
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Official Solution:

The first flight out of Phoenix airport had a late departure. If the next three flights departed on-time, how many subsequent flights need to depart from Phoenix on-time, for the airport's on-time departure rate to be higher than 90%?

A. 6
B. 7
C. 9
D. 10
E. 11

We need on-time departure rate to be higher than \(\frac{9}{10}\), so it should be at least \(\frac{10}{11}\), which means that 10 out of 11 flights must depart on time. Since for now 3 out of 4 flights departed on time then \(10-3=7\) subsequent flights need to depart on-time.

Answer: B
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Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

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Re M06-03 [#permalink]

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New post 11 Feb 2015, 13:36
I think this question is poor and not helpful.
it is not clear "subsequent" to which number: the 1 flight late, or the 3 flight on time.
can be formulated "how many more subsequent flights..."
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Re: M06-03 [#permalink]

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New post 02 May 2015, 06:34
Let x be subsequent flights need to depart from Phoenix on-time.
To the airport's on-time departure rate to be higher than 90%: 3+x/4+x >0.9 => 0.1x>0.6 => x>6, x=7.
Is it right.
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Re M06-03 [#permalink]

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New post 16 Sep 2015, 02:18
I think this is a poor-quality question and I don't agree with the explanation.
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Re: M06-03 [#permalink]

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New post 16 Sep 2015, 02:42
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Re: M06-03 [#permalink]

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New post 15 Oct 2015, 10:24
This is a very straightforward question. For the % to be > 90, we need atleast 10 flights on time (as 1 was delayed). 3 of those 10 were on-time, hence 7 more are required.
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Re M06-03 [#permalink]

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New post 04 Apr 2016, 05:06
I think this is a poor-quality question and I agree with explanation. somehow agree . I think "minimum" should be added be fore on-time because otherwise 9,10,11 subsequent flights also make a on-time departure rate higher then 90%
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Re: M06-03 [#permalink]

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New post 04 Apr 2016, 05:19
deospaima wrote:
I think this is a poor-quality question and I agree with explanation. somehow agree . I think "minimum" should be added be fore on-time because otherwise 9,10,11 subsequent flights also make a on-time departure rate higher then 90%


Hi,
1) firstly I really don't understand why it is a Poor Q. It is a very normal Q.
2) Yes, minimum would have made things more clearer. BUT when we sayhow many subsequent flights need to depart from Phoenix on-time, for the airport's on-time departure rate to be higher than 90%?, I think it conveys the same meaning..
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Re: M06-03 [#permalink]

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New post 04 Apr 2016, 08:32
when you send feedback from CATs in Gmat Club if you tick "poor questions" it automatically ads this to the thread..so actually I don't find it a poor questions , I just think it should be more clear. honestly I don't agree with this :

BUT when we sayhow many subsequent flights need to depart from Phoenix on-time, for the airport's on-time departure rate to be higher than 90%?, I think it conveys the same meaning..

in GMAT questions I think you shouldn't have 2 answers that verify the conditions..and here we have multiple ones..just my opinion :)
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Re: M06-03 [#permalink]

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New post 10 Jun 2016, 08:53
Bunuel wrote:
prodigypringle wrote:
I think this is a poor-quality question and I don't agree with the explanation.


Please elaborate WHY do you think that the question is of poor-quality. Thank you.


Bunuel, I believe this is a good question however it seems to me that "subsequent" is used in a vague manner. Subsequent from the first flight (10-4=6 additional on-time flights needed to bring % to 90) or subsequent from the FIRST on-time flight (10-3=7 additional flights needed to bring percentage to 90)?

I chose 6 as my answer because I was counting all subsequent flights from the first late departure.

Aside from this I do think it is a good question
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Re: M06-03 [#permalink]

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New post 25 Aug 2016, 13:10
I think this question tests your verbal skills also , and i got it wrong too .

But for those who believe that the language is inappropriate , its not.

If the next three flights departed on-time, how many subsequent flights need to depart from Phoenix on-time, for the airport's on-time departure rate to be higher than 90%?
The underlined portion is clearly making a play on the "next three flights" , and the significance of the word "need" is to mean that we "need" to find the minimum number of more subsequent flights.
I hope everyone got my point. ;)
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Re: M06-03 [#permalink]

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Bunuel wrote:
The first flight out of Phoenix airport had a late departure. If the next three flights departed on-time, how many subsequent flights need to depart from Phoenix on-time, for the airport's on-time departure rate to be higher than 90%?

A. 6
B. 7
C. 9
D. 10
E. 11


Here's my take on this:

Current stat:
1 on time
3 late

current % of on time departure: 3/4 = 75%

We need >90%, hence let's keep adding more flights that departed on time.

(3+1)/(4+1) = 4/5 = 80% not over to 90%
(3+2)/(4+2) = 5/6 not over to 90%
(3+3)/(4+3) = 6/7 not over to 90%
(3+4)/(4+4) = 7/8 not over to 90%
(3+5)/(4+5) = 8/9 not over to 90%
(3+6)/(4+6) = 9/10 = 90% not over to 90%
(3+7)/(4+7) = 10/11 just over to 90%

Hence 7 is the answer.
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Re: M06-03 [#permalink]

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New post 06 Sep 2017, 01:24
Bunuel and abhimahna

What I understood from this question was:
Total= 4 flights (till now)
On time= 3

Therefore 3/4*100= 75% on time

For this percentage to be >90%:

If 6 more flights take off on time, then there will be total 6+3 flights that took off on time.

Total= 6+3+1= 10
On time= 9
Percentage= 9/10*100 = 90%

What did I miss? Is it the "subsequent" information that I misinterpreted?
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Re: M06-03 [#permalink]

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New post 06 Sep 2017, 01:26
I think I somewhat get it:

We need more than 90% and option A gives exactly 90%.
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Re: M06-03 [#permalink]

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New post 02 Jan 2018, 21:17
Bunuel wrote:
Official Solution:

The first flight out of Phoenix airport had a late departure. If the next three flights departed on-time, how many subsequent flights need to depart from Phoenix on-time, for the airport's on-time departure rate to be higher than 90%?

A. 6
B. 7
C. 9
D. 10
E. 11

We need on-time departure rate to be higher than \(\frac{9}{10}\), so it should be at least \(\frac{10}{11}\), which means that 10 out of 11 flights must depart on time. Since for now 3 out of 4 flights departed on time then \(10-3=7\) subsequent flights need to depart on-time.

Answer: B


Bunuel, could you explain how did you come to 10/11. I am not able to get above highlighted red part.
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Re: M06-03 [#permalink]

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New post 02 Jan 2018, 22:27
ammuseeru wrote:
Bunuel wrote:
Official Solution:

The first flight out of Phoenix airport had a late departure. If the next three flights departed on-time, how many subsequent flights need to depart from Phoenix on-time, for the airport's on-time departure rate to be higher than 90%?

A. 6
B. 7
C. 9
D. 10
E. 11

We need on-time departure rate to be higher than \(\frac{9}{10}\), so it should be at least \(\frac{10}{11}\), which means that 10 out of 11 flights must depart on time. Since for now 3 out of 4 flights departed on time then \(10-3=7\) subsequent flights need to depart on-time.

Answer: B


Bunuel, could you explain how did you come to 10/11. I am not able to get above highlighted red part.


We need (on-time departures)/(total departures) to be greater than 9/10. Next, fraction, which is greater than 9/10 (having both numerator and denominator integers) is 10/11:

9/10 < 10/11 < 11/12 < ...
9/10 < 10/11 < 91/100 < ...
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


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Re: M06-03   [#permalink] 02 Jan 2018, 22:27
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