In the first 2 hours after Meadow's self-service laundry

This topic has expert replies
Moderator
Posts: 7187
Joined: Thu Sep 07, 2017 4:43 pm
Followed by:23 members
In the first 2 hours after Meadow's self-service laundry opens, m large washing machines and n small washing machines are in continual use. Including the time for filling and emptying the washing machines, each load of laundry takes 30 minutes in a large washing machine and 20 minutes in a small washing machine. What is the total number of loads of laundry done at Meadow's self-service laundry during this 2-hour period?

(1) n = 3m
(2) 2m + 3n = 55


OA B

Source: Official Guide
Source: — Data Sufficiency |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3008
Joined: Mon Aug 22, 2016 6:19 am
Location: Grand Central / New York
Thanked: 470 times
Followed by:34 members

by Jay@ManhattanReview » Thu Dec 12, 2019 9:43 pm
BTGmoderatorDC wrote:In the first 2 hours after Meadow's self-service laundry opens, m large washing machines and n small washing machines are in continual use. Including the time for filling and emptying the washing machines, each load of laundry takes 30 minutes in a large washing machine and 20 minutes in a small washing machine. What is the total number of loads of laundry done at Meadow's self-service laundry during this 2-hour period?

(1) n = 3m
(2) 2m + 3n = 55

OA B

Source: Official Guide
Given that each load of laundry takes 30 minutes in a large washing machine, in 2 hours, there will be 4 loads per machine. Since there are m large machines, there would be 4m load; similarly, given that each load of laundry takes 20 minutes in a small washing machine, in 2 hours, there will be 6 loads per machine. Since there are n small machines, there would be 6n load.

Thus, total number of load = 4m + 6n.

So, we have to get the value of 4m + 6n.

Let's take each statement one by one.

(1) n = 3m

total number of load = 4m + 6n = total load = 4m + 6*3m = 22m. Can't get the value. Insufficient.

(2) 2m + 3n = 55

=> total number of load = 4m + 6n = 2(2m + 3n) = 2*55 = 110. Sufficient.

The correct answer: B

Hope this helps!

-Jay
_________________
Manhattan Review GRE Prep

Locations: GRE Classes Raleigh NC | GRE Prep Course Singapore | GRE Prep Philadelphia | SAT Prep Classes Toronto | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.

Legendary Member
Posts: 2214
Joined: Fri Mar 02, 2018 2:22 pm
Followed by:5 members

by deloitte247 » Thu Dec 19, 2019 11:45 pm
Large machine = m
Small machine = n
Given that load of laundry for 'm' takes 30 minutes, and load of laundry for 'n' takes 20 minutes.
2 hours = 2 * 60 minutes = 120 minutes
For m in 2 hours = 120/30 = 4
For n in 2 hours = 120/20 = 6
m loads in 2 hours = 4m
n loads in 2 hours = 6n
What is the total number of loads of laundry done at Meadow's self-service laundry during this 2-hour period?
i.e 4m + 6n = ??
Statement 1: n = 3m
4m + 6 (3m) = x
4m + 18m = x
x = 22m
However, the value of m is unknown, hence, statement 1 is NOT SUFFICIENT.

Statement 2: 2m + 3n = 55
Multiply through by 2
4m + 6n = 110
The total loads in 2 hours = 110 laundries. Thus, statement 2 alone is SUFFICIENT.

The correct answer, therefore, is option B.