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

 It is currently 22 Mar 2019, 15:57

### 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
Your Progress

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

# A bus stop is served by express buses, which run every hour

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

### Hide Tags

Manager
Joined: 20 Dec 2004
Posts: 246
A bus stop is served by express buses, which run every hour  [#permalink]

### Show Tags

27 Jan 2008, 19:35
1
9
00:00

Difficulty:

(N/A)

Question Stats:

33% (03:05) correct 67% (02:58) wrong based on 19 sessions

### HideShow timer Statistics

A bus stop is served by express buses, which run every hour at ten minutes past the hour, and local buses, which run every quarter of an hour, starting at five past the hour. What is the probability that a passenger arriving at the stop at random will have to wait more than six minutes for a bus?

OA:
31/60.

_________________

Stay Hungry, Stay Foolish

##### Most Helpful Expert Reply
CEO
Joined: 17 Nov 2007
Posts: 3420
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
Re: A bus stop is served by express buses, which run every hour  [#permalink]

### Show Tags

27 Jan 2008, 21:56
9
3
$$p=\frac{9+9+9+4}{60}=\frac{31}{60}$$
Attachments

t59157.gif [ 15.48 KiB | Viewed 3765 times ]

_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | Limited GMAT/GRE Math tutoring in Chicago

##### General Discussion
Director
Joined: 03 Sep 2006
Posts: 777
Re: A bus stop is served by express buses, which run every hour  [#permalink]

### Show Tags

27 Jan 2008, 21:47
neelesh wrote:
A bus stop is served by express buses, which run every hour at ten minutes past the hour, and local buses, which run every quarter of an hour, starting at five past the hour. What is the probability that a passenger arriving at the stop at random will have to wait more than six minutes for a bus?

I do have the OA but not sure how to arrive at that and hence looking for an explanation.

P = (4/60) + ( 4/60) + ( 9/60) + ( 9/60) + (10/60) = 36/60 = 3/5
Attachments

Bus Probability.PNG [ 19.92 KiB | Viewed 3768 times ]

SVP
Joined: 04 May 2006
Posts: 1645
Schools: CBS, Kellogg
Re: A bus stop is served by express buses, which run every hour  [#permalink]

### Show Tags

27 Jan 2008, 22:07
walker wrote:
$$p=\frac{9+9+9+4}{60}=\frac{31}{60}$$

I am in the dark of this picture! I have the same start point, but do not know how to make the likelihood of it! help!
_________________
Director
Joined: 03 Sep 2006
Posts: 777
Re: A bus stop is served by express buses, which run every hour  [#permalink]

### Show Tags

27 Jan 2008, 22:30
walker wrote:
$$p=\frac{9+9+9+4}{60}=\frac{31}{60}$$

Thanks walker, mistake in my case is that the last slot of 10 minutes is not needed which I have taken in my calculations.

If I remove that then it would be same and if I add that, then I am moving to the next hor slot!
Manager
Joined: 20 Dec 2004
Posts: 246
Re: A bus stop is served by express buses, which run every hour  [#permalink]

### Show Tags

27 Jan 2008, 23:19
Excellent explanation Walker.

Does this seem like a 2-minute type question ?
_________________

Stay Hungry, Stay Foolish

CEO
Joined: 17 Nov 2007
Posts: 3420
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
Re: A bus stop is served by express buses, which run every hour  [#permalink]

### Show Tags

27 Jan 2008, 23:26
neelesh wrote:
Does this seem like a 2-minute type question ?

I guess yes. But I spent more than 15 min to draw it in PhotoShop....
_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | Limited GMAT/GRE Math tutoring in Chicago

Director
Joined: 14 Oct 2007
Posts: 720
Location: Oxford
Schools: Oxford'10
Re: A bus stop is served by express buses, which run every hour  [#permalink]

### Show Tags

28 Jan 2008, 13:32
neelesh wrote:
Excellent explanation Walker.

Does this seem like a 2-minute type question ?

It took about a minute,
i did a number line (made sure I take into account the last block properly).

btw, nice photoshop skills walker...is there something you are NOT good at?

(i am betting this guy is a killer soccer player!)
CEO
Joined: 17 Nov 2007
Posts: 3420
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
Re: A bus stop is served by express buses, which run every hour  [#permalink]

### Show Tags

28 Jan 2008, 13:42
buffdaddy wrote:
is there something you are NOT good at?

(i am betting this guy is a killer soccer player!)

No . If I were a killer soccer player I would play in Manchester United and have a lot of money!
_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | Limited GMAT/GRE Math tutoring in Chicago

Director
Joined: 01 Jan 2008
Posts: 588
Re: A bus stop is served by express buses, which run every hour  [#permalink]

### Show Tags

28 Jan 2008, 14:25
30 sec solution: 1-(4*6+5)/60 = 31/60
Intern
Joined: 03 Jan 2014
Posts: 1
Re: A bus stop is served by express buses, which run every hour  [#permalink]

### Show Tags

25 Jan 2014, 07:06
At minutes 10, 20, 35 and 50 - wouldnt you have to wait zero minutes for the bus.

Which is why the calculation should not include those 4 minutes. In other words the sum should be: 8 + 8 + 8 + 3 = 27

And the probability = 27/60?
Intern
Joined: 09 Sep 2014
Posts: 6
A bus stop is served by express buses, which run every hour  [#permalink]

### Show Tags

20 Oct 2014, 15:59
I am confused because I have a different answer...

|----5---10----20----30----35----40-----50----|

10,10,10,10 are the only open times it is possible to wait 6+ minutes

It is allowed 6 minutes that the person can wait before they are counted

4+4+4+4 = 16/60 = 4/15

Yet this is wrong?
Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 9007
Location: Pune, India
Re: A bus stop is served by express buses, which run every hour  [#permalink]

### Show Tags

20 Oct 2014, 20:42
adaptari wrote:
At minutes 10, 20, 35 and 50 - wouldnt you have to wait zero minutes for the bus.

Which is why the calculation should not include those 4 minutes. In other words the sum should be: 8 + 8 + 8 + 3 = 27

And the probability = 27/60?

Say, 6:10 am is a point in time. It does not represent a whole minute.
6:10 to 6:11 represents a minute.
A bus arrives at 6:10 and the next one arrives at 6:20. A person who reaches the bus stop between 6:10 to 6:14 will need to wait for more than 6 mins.
6:10 to 6:14 represents 4 mins:
6:10 to 6:11,
6:11 to 6:12,
6:12 to 6:13 and
6:13 to 6:14

Similarly, a person arriving between 6:20 and 6:29 will need to wait for more than 6 mins. This time interval is 9 mins.
_________________

Karishma
Veritas Prep GMAT Instructor

Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >

Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 9007
Location: Pune, India
Re: A bus stop is served by express buses, which run every hour  [#permalink]

### Show Tags

20 Oct 2014, 20:52
1
silhouette wrote:
I am confused because I have a different answer...

|----5---10----20----30----35----40-----50----|

10,10,10,10 are the only open times it is possible to wait 6+ minutes

It is allowed 6 minutes that the person can wait before they are counted

4+4+4+4 = 16/60 = 4/15

Yet this is wrong?

How did you get 30 and 40? The express buses run every hour starting at 10 mins past. So the express buses run only at 10 mins past.
Local buses run every 15 mins starting at 5 mins past so they run at 5, 20, 35 and 50 mins past the hour.

So buses run at following mins past the hour:
...5....10...20....35....50

This means a person arriving between 10 and 14, 20 and 29, 35 and 44, and 50 and 59 must wait for more than 6 mins.
4 + 9 + 9+ 9 = 31 mins

Probability = 31/60
_________________

Karishma
Veritas Prep GMAT Instructor

Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >

Intern
Joined: 09 Sep 2014
Posts: 6
Re: A bus stop is served by express buses, which run every hour  [#permalink]

### Show Tags

21 Oct 2014, 19:29
VeritasPrepKarishma wrote:
How did you get 30 and 40?

I thought the buses came every ten minutes! But now I see where I was wrong. Thank you for explaining. Your insight is always appreciated. Thank you!!
Non-Human User
Joined: 09 Sep 2013
Posts: 10184
Re: A bus stop is served by express buses, which run every hour  [#permalink]

### Show Tags

05 Mar 2019, 07:22
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 bus stop is served by express buses, which run every hour   [#permalink] 05 Mar 2019, 07:22
Display posts from previous: Sort by

# A bus stop is served by express buses, which run every hour

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.