BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

elevator

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 234
Joined: Fri Oct 01, 2010 7:28 pm
Location: chennai
Thanked: 5 times
Followed by:4 members

elevator

by pappueshwar » Thu Mar 22, 2012 9:48 am
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

OA IS D. pls assist
Top
Source: — Problem Solving |
Legendary Member
Posts: 581
Joined: Sun Apr 03, 2011 7:53 am
Thanked: 52 times
Followed by:5 members

by killer1387 » Thu Mar 22, 2012 10:10 am
pappueshwar 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

OA IS D. pls assist
FOR the first complete trip time taken=10/4+1+10/4=6 min

for second trip= 1+10/4+10/4+1=7 min
for third=7 and so on

let there be x no of 7 min trips,

then

6+7x=7*60
x=59.14

hence total complete trips of 7 min= 59
hence total trips = 7 min trips+6 min trip=59+1=60

hence D
Top
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Thu Mar 22, 2012 11:30 am
pappueshwar 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

OA IS D. pls assist
10 floors are passed on the way up (floors 2-11), and 10 floors passed on the way down (floors 10-1).
Thus, 1 complete trip = 20 floors.
At a rate of 1/4 minute per floor, the time for 20 floors = 20/4 = 5 minutes.
Since there is a 1-minute stop at the top and a 1-minute stop at the bottom, the total time per trip = 5+1+1 = 7 minutes.
In 7 hours -- which is 420 minutes -- the number of trips = 420/7 = 60.

The correct answer is D.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
User avatar
GMAT Instructor
Posts: 1462
Joined: Thu Apr 09, 2015 9:34 am
Location: New York, NY
Thanked: 39 times
Followed by:22 members

by Jeff@TargetTestPrep » Thu Dec 07, 2017 10:20 am
pappueshwar 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.

Answer: D

Jeffrey Miller
Head of GMAT Instruction
[email protected]

Image

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews
Top
Post new topic Post Reply
• Page 1 of 1