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# The elevator in an eleven-story office building travels at

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Status: mba here i come!
Joined: 07 Aug 2011
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The elevator in an eleven-story office building travels at  [#permalink]

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Updated on: 22 Jul 2013, 05:27
5
20
00:00

Difficulty:

95% (hard)

Question Stats:

29% (02:47) correct 71% (03:02) wrong based on 425 sessions

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The elevator in an eleven-story office building travels at the rate of one floor per 1/4 minute, which allows time for picking up and discharging passengers. At the main floor and at the top floor, the operator stops for 1 minute. How many complete trips will an operator make during a 7-hour period?

A) 88
B) 56
C) 42
D) 60
E) 64

Originally posted by MBAhereIcome on 23 Aug 2011, 03:25.
Last edited by Bunuel on 22 Jul 2013, 05:27, edited 1 time in total.
RENAMED THE TOPIC.
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Joined: 02 Sep 2009
Posts: 60778
Re: The elevator in an eleven-story office building travels at  [#permalink]

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24 Apr 2014, 01:36
5
6
JusTLucK04 wrote:
60*2= Main + 11 Floor
15*9= 135 Sec for 9 Floors

Total= 9+2 = 11 floors

Wat am I missing here..Coz 390 secs per trip does not lead to 60 trips in 7 hrs

The elevator in an eleven-story office building travels at the rate of one floor per 1/4 minute, which allows time for picking up and discharging passengers. At the main floor and at the top floor, the operator stops for 1 minute. How many complete trips will an operator make during a 7-hour period?

A) 88
B) 56
C) 42
D) 60
E) 64

Complete trip = 10 floors up and 10 floors down = 20 floors = 20*1/4 = 5 minutes plus 2 minutes = 7 minutes.

7 hour = 420 minutes.

In 420 minutes operator can make 420/7=60 trips.

Hope it's clear.
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Joined: 27 Jul 2011
Posts: 20
Re: complete building trips by an elevator  [#permalink]

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23 Aug 2011, 04:01
3
The answer is 60 (option D)
1----2-----3----4----5----6----7----8----9----10----11
0 1.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25

So the liftman will take 3.5 min for one way, so for complete trip, he will take 7 min.
(1.25 at the start is the lift rate + ome minute wait).

So, In 60 min,
The liftman will complete (60/7) trips.

therefore, in 7 hours, the number of complete trips will be (60/7)*7 ie 60 trips.
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Re: complete building trips by an elevator  [#permalink]

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27 Aug 2011, 07:55
1
Ground floor (Main): 1 minute
Floor 1 - 10..........: 0.25 each * 10 floors = 2.5 mins per direction * 2 = 5 mins per round
Floor 11 (Top).......: 1 minute
=======================
..........................: 7 minutes per ride

7 * 60 mins = 420 mins in total

420/7 = 60

Even though it's a bit weird because in the first round, nobody has to leave and in the last round nobody enters
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Re: The elevator in an eleven-story office building travels at  [#permalink]

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23 Apr 2014, 22:10
2
Thanks Gmatclub..I got more knowledge here for related to elevators.
Yes ....And I am agree with you that it will do 60 trip in 7 hours.
I want to say something about my services. We are also providing Home elevators and office elevators.
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Re: The elevator in an eleven-story office building travels at  [#permalink]

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23 Apr 2014, 22:52
60*2= Main + 11 Floor
15*9= 135 Sec for 9 Floors

Total= 9+2 = 11 floors

Wat am I missing here..Coz 390 secs per trip does not lead to 60 trips in 7 hrs
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Re: The elevator in an eleven-story office building travels at  [#permalink]

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24 Apr 2014, 01:42
So you included the 15 seconds for the ground floor/top floor too...for 1complete up-down trip?..I am counting it for just 9 floors
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Re: The elevator in an eleven-story office building travels at  [#permalink]

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24 Apr 2014, 03:04
4
1
JusTLucK04 wrote:
So you included the 15 seconds for the ground floor/top floor too...for 1complete up-down trip?..I am counting it for just 9 floors

Think below might help:

(1st floor = 1 minute)
(1/4 minutes to 2nd floor) 1
(1/4 minutes to 3rd floor) 2
(1/4 minutes to 4th floor) 3
(1/4 minutes to 5th floor) 4
(1/4 minutes to 6th floor) 5
(1/4 minutes to 7th floor) 6
(1/4 minutes to 8th floor) 7
(1/4 minutes to 9th floor) 8
(1/4 minutes to 10th floor) 9
(1/4 minutes to 11th floor) 10

(11th floor = 1 minute)
(1/4 minutes to 10th floor) 1
(1/4 minutes to 9th floor) 2
(1/4 minutes to 8th floor) 3
(1/4 minutes to 7th floor) 4
(1/4 minutes to 6th floor) 5
(1/4 minutes to 5th floor) 6
(1/4 minutes to 4th floor) 7
(1/4 minutes to 3rd floor) 8
(1/4 minutes to 2nd floor) 9
(1/4 minutes to 1st floor) 10

Complete trip = 20 1/4-minute intervals + 2 minutes = 7 minutes.

Does this make sense?
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Re: The elevator in an eleven-story office building travels at  [#permalink]

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24 Apr 2014, 03:16
Got it..my interpretation was wrong
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Re: The elevator in an eleven-story office building travels at  [#permalink]

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02 Oct 2014, 02:33
88 trips?
Here's how I did it.
11*.25+2=1 complete trip=4.75 min
7*60=minutes in time period=420
420/4.75=88.42 trips
Don't know if that's right
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Re: The elevator in an eleven-story office building travels at  [#permalink]

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08 Jun 2015, 19:42
i don't understand..Why are we starting from 1st Floor... We need to start from Ground floor.... Now Ground to 1st, 1st to 2nd ... similarly for 11 floors .. it should be 11 * .25 min ... its not 10 floor up and 10 floors down.. its 11 floors up an 11 floors down.. as per this.. the answer should be 56
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Re: The elevator in an eleven-story office building travels at  [#permalink]

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09 Jun 2015, 15:00
Quote:
The elevator in an eleven-story office building travels at the rate of one floor per 1/4 minute, which allows time for picking up and discharging passengers. At the main floor and at the top floor, the operator stops for 1 minute. How many complete trips will an operator make during a 7-hour period?

A) 88
B) 56
C) 42
D) 60
E) 64

1 floor / 1 / 4 minute
So; 4 floors per minute,
The building is 11 floors so it would take the elevator 2 3/4 minutes for a full trip, now we add the waiting time on the two floors, so it would be 4 3/4 minutes for a full round trip.
60*7 / 4 3/4 = roughly 88

But I think there should be an easier way to calculate.
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Re: The elevator in an eleven-story office building travels at  [#permalink]

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16 Nov 2016, 10:15
MBAhereIcome wrote:
The elevator in an eleven-story office building travels at the rate of one floor per 1/4 minute, which allows time for picking up and discharging passengers. At the main floor and at the top floor, the operator stops for 1 minute. How many complete trips will an operator make during a 7-hour period?

A) 88
B) 56
C) 42
D) 60
E) 64

This question is not complicated. I think the wording does not make things clear. It must mention that before the lift goes up for the first time ever, it stops for 1 minute. Similarly, when the lift lands for the last time at the ground floor, it again waits for 1 minute. Without this, the calculations will not fall in place for 7 minutes per every trip. Bunuel Please see.
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Re: The elevator in an eleven-story office building travels at  [#permalink]

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18 Nov 2016, 08:03
MBAhereIcome wrote:
The elevator in an eleven-story office building travels at the rate of one floor per 1/4 minute, which allows time for picking up and discharging passengers. At the main floor and at the top floor, the operator stops for 1 minute. How many complete trips will an operator make during a 7-hour period?

A) 88
B) 56
C) 42
D) 60
E) 64

We are given that an elevator takes 1/4 minute to travel between floors and that it stops for one minute at the top floor and also on the main floor. Since the elevator is traveling from the main floor to the 11th floor, it’s traveling 10 total floors.

Thus, the total time it takes for the elevator to go from the bottom floor to the 11th floor and back down is:

20 x 1/4 = 5 minutes

Since the elevator stops for a minute each at the top and main floors, the amount of time to complete a trip is:

5 + 2 = 7 minutes = 7/60 hours

Thus, in 7 hours the elevator can complete 7/(7/60) = 60 trips.

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Re: The elevator in an eleven-story office building travels at  [#permalink]

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22 Jun 2019, 10:31
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Re: The elevator in an eleven-story office building travels at   [#permalink] 22 Jun 2019, 10:31
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