GMAT Paper Tests
A certain hotel has 1,400 single rooms and 420 double rooms. Each room is cleaned by one person. If one person can clean a single room every 15 minutes and a double room every 20 minutes, how many cleaning persons are needed to clean all the rooms if each person works for exactly 7 hours?
A. 65
B. 70
C. 80
D. 90
E. 265
OA B
A certain hotel has 1,400 single rooms and 420 double rooms.
This topic has expert replies
GMAT/MBA Expert
- Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
The hotel has 1,400 single rooms, and one person can clean a single room every 15 minutesAAPL wrote:GMAT Paper Tests
A certain hotel has 1,400 single rooms and 420 double rooms. Each room is cleaned by one person. If one person can clean a single room every 15 minutes and a double room every 20 minutes, how many cleaning persons are needed to clean all the rooms if each person works for exactly 7 hours?
A. 65
B. 70
C. 80
D. 90
E. 265
OA B
So, one person can clean 4 single rooms in ONE HOUR
In other words, it takes 1 WORKER HOUR to clean 4 single rooms
1400/4 = 350
So, it takes 350 WORKER HOURS to clean 1400 rooms
The hotel has 420 double rooms, and one person can clean a double room every 20 minutes
So, one person can clean 3 double rooms in ONE HOUR
In other words, it takes 1 WORKER HOUR to clean 3 double rooms
420/3 = 140
So, it takes 140 WORKER HOURS to clean 420 double rooms
How many cleaning persons are needed to clean all the rooms if each person works for exactly 7 hours?
350 + 140 = 490
So, 490 WORKER HOURS are required to clean ALL of the room.
490/7 = 70.
So, 70 workers are needed.
Answer: B
Cheers,
Brent
GMAT/MBA Expert
- Scott@TargetTestPrep
- GMAT Instructor
- Posts: 7266
- Joined: Sat Apr 25, 2015 10:56 am
- Location: Los Angeles, CA
- Thanked: 43 times
- Followed by:29 members
It takes 1400 x 1/4 = 350 hours to clean the single rooms and 420 x 1/3 = 140 hours to clean the double rooms, for a total time of 490 hours. We can let n = the number of workers and create the equation:AAPL wrote:GMAT Paper Tests
A certain hotel has 1,400 single rooms and 420 double rooms. Each room is cleaned by one person. If one person can clean a single room every 15 minutes and a double room every 20 minutes, how many cleaning persons are needed to clean all the rooms if each person works for exactly 7 hours?
A. 65
B. 70
C. 80
D. 90
E. 265
OA B
7n = 490
n = 70
Answer: B
Scott Woodbury-Stewart
Founder and CEO
[email protected]
See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews
GMAT/MBA Expert
- [email protected]
- Elite Legendary Member
- Posts: 10392
- Joined: Sun Jun 23, 2013 6:38 pm
- Location: Palo Alto, CA
- Thanked: 2867 times
- Followed by:511 members
- GMAT Score:800
Hi camitava,
This is essentially a rate question. Here's how to solve it:
Single rooms take one person 15 minutes to clean and double rooms take one person 20 minutes to clean.
15 mins. = 1/4 hour
20 mins. = 1/3 hour
With 1400 single rooms x 1/4 hour = 350 hours of total work for 1 person
With 420 double rooms x 1/3 hour = 140 hours of total work for 1 person
For ALL the rooms, we have a total of 350 + 140 = 490 hours of total work for 1 person
To get the work done in 7 hours, we'll need 490/7 = 70 workers
Final Answer: B
GMAT assassins aren't born, they're made,
Rich
This is essentially a rate question. Here's how to solve it:
Single rooms take one person 15 minutes to clean and double rooms take one person 20 minutes to clean.
15 mins. = 1/4 hour
20 mins. = 1/3 hour
With 1400 single rooms x 1/4 hour = 350 hours of total work for 1 person
With 420 double rooms x 1/3 hour = 140 hours of total work for 1 person
For ALL the rooms, we have a total of 350 + 140 = 490 hours of total work for 1 person
To get the work done in 7 hours, we'll need 490/7 = 70 workers
Final Answer: B
GMAT assassins aren't born, they're made,
Rich