Printing press X can print an edition of a newspaper in 12 hours, wher

Question

Printing press X can print an edition of a newspaper in 12 hours, whereas press Y can print the same edition in 18 hours. What is the total number of hours that it will take the two presses, working together but independently of one another, to print the same edition?

A. 15
B. 7.4
C. 7.2
D. 7.0
E. 6.8

PS20370

A. 15
B. 7.4
C. 7.2
D. 7.0
E. 6.8

PS20370

Archit3110 · Answer

combined rate = 1/12 + 1/18 ; 10/72
7.2 hrs
OPTION C

BrentGMATPrepNow · Answer

Let's  assign a "nice value"  to the job a printing an edition of a newspaper.
We're looking for a number that works well with the given information: 12 hours and 18 hours
Since   36   is the least common multiple of 12 and 18, let's say the job requires the printing presses to print a total of   36   newspapers

Printing press X can print an edition of a newspaper in 12 hours  
In other words, printing press X can print   36   newspapers in 12 hours
So, its RATE =  3  newspapers per HOUR

Printing press Y can print an edition of a newspaper in 18 hours  
In other words, printing press Y can print   36   newspapers in 18 hours
So, its RATE =  2  newspapers per HOUR

What is the total number of hours that it will take the two presses, working together but independently of one another, to print the same edition?  
The combined RATE of the two printing presses =  3  +  2  =   5   newspapers per HOUR

Time = output/rate 
So the time to print 36 newspapers =   36  /  5   =  7.2

Answer: C

Cheers,
Brent

NitishJain · Answer

C.
Work Rate for X: 1/12
Work Rate for Y: 1/18
Combined Rate: 1/12+1/18 = 5/36
Time: 36/5 = 7.2 hours

GDT · Answer

Rate of X=1/12 job per hr

Rate of X=1/18 job per hr

Combined rate =1/12+1/18=5/36 job per hr

Now we know T=W/R=36/5=7.2 hrs

itachiuchiha · Answer

To make the calculations easier, let's take the total work as LCM(12,18) = 36 units of work.

Now, printing press X does =  \frac{36}{12} = 3  units of work in an hour

printing press Y does =  \frac{36}{18} = 2  units of work in an hour

When both these machines work together then the total amount of work done in an hour =  3 + 2 = 5  units of work.

Total hours taken to complete the work =  \frac{36}{5}  = 7.2 hours.

IMO, OA - C

EgmatQuantExpert · Answer

Solution 
 
  Given  
• Printing press X can print an edition of a newspaper in 12 hours 
• Press Y can print the same edition in 18 hours
  To find  
• The total number of hours that it will take the two presses, working together but independently of one another, to print the same edition

Approach and Working out   
• Printing Press X
 o 12 hours -- 1 edition
o 1 hour – 1/12 edition 
• Printing Press Y
 o 18 hours -- 1 edition
o 1 hour – 1/18 edition 
• Press X and Y together
 o 1 hour – (1/12) + (1/18) edition
  That is 1 hour – (5/36) edition
 Hence, 1 edition – 36/5 hours = 7.2 hours

Correct Answer: Option C

DanTheGMATMan · Answer

Standard combined work problem:
 https://www.youtube.com/watch?v=LuQTumlzQUw

Goal700 · Answer

Can you please explain this:
 
 That is 1 hour – (5/36) edition Hence, 1 edition – 36/5 hours = 7.2 hours?Thank you so much!

Bunuel · Answer

In 1 hour, 5/36 editions are printed.

To get the time for 1 edition, divide by 5/36:

5/36 editions = 1 hour

=  .

Printing press X can print an edition of a newspaper in 12 hours, wher

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Printing press X can print an edition of a newspaper in 12 hours, wher

Prep Toolkit

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