M24 Q 24

icandy · **Posted:** Thu Mar 12, 2009 1:54 pm

In normal printing mode, 20 printers can print 100 pages in 3 minutes. In economy mode, printers work 20% faster than in normal mode. How many printers are required to print 180 pages in 3 minutes in economy mode?

(A) 25
(B) 28
(C) 29
(D) 30
(E) 32

[Reveal] Spoiler: OA

D

Source: GMAT Club Tests - hardest GMAT Questions

I pulled this off but I want to hear from folks on their approaches

x2suresh · **Posted:** Thu Mar 12, 2009 5:55 pm

icandy wrote:

I pulled this off but I want to hear from folks on their approaches

In normal printing mode, 20 printers can print 100 pages in 3 minutes. In economy mode, printers work 20% faster than in normal mode. How many printers are required to print 180 pages in 3 minutes in economy mode?

(C) 2008 GMAT Club - m24#24

* 25
* 28
* 29
* 30
* 32

normal mod = 100/20*3 = 5/3 PAGES/printer/minute

economy mode printer rate = 5/3 *1.2 = 2 pages/printer/minute

priner rate for 3 minutes = 6 pages/printer = 180 pages /30 printers

30

D

Economist · **Posted:** Sun Apr 05, 2009 2:14 am

Normal mode rate = 100/(3*20)
Economy mode rate = 1.20 * 100/(3*20)

Now, let x be the number of economy mode printers.
Adding rates of all printers = Combined rate of printers

x * 1.20 * 100/(3*20) = 180/3
=>x = 30

patedhav · **Posted:** Mon Mar 16, 2009 8:46 am

icandy wrote:

I pulled this off but I want to hear from folks on their approaches

In normal printing mode, 20 printers can print 100 pages in 3 minutes. In economy mode, printers work 20% faster than in normal mode. How many printers are required to print 180 pages in 3 minutes in economy mode?

(C) 2008 GMAT Club - m24#24

* 25
* 28
* 29
* 30
* 32

Method:

1) First find out the time required to print 1 page in 3 Minutes (here 3 Minutes because answer ask for the same) with 1 printer and you will find one printer prints 6 pages in 3 minutes after their percentage increase in economical speed.

(100 / 20) * (120 / 100) = 6 pages.

2) Once you find this it is easy to find for 180 pages how many printer requires. (30).

2) Once you find 6

gmatdreamz · **Posted:** Fri Mar 20, 2009 12:18 pm

In economy mode printers print 20% faster. Hence 20 printers will print 120 pages in 3 mins. You want 1.5 times of 120 pages, hence you multiply 1.5 * 20 printers (and don't touch the time at all, as we want to find out the number of pages in 3 mins) = 30 printers.

Hence, ANS - 30 printers

lgon · **Posted:** Thu Apr 09, 2009 11:29 pm

20 printer, 100 page, 3 minutes
1 printer, 5 page, 3 minutes
in economy it is 20% faster
so,
1 printer, 5+1 page , 3 minutes
30 printer, 180 page, 3 minutes.
D is the answer

icandy wrote:

I pulled this off but I want to hear from folks on their approaches

In normal printing mode, 20 printers can print 100 pages in 3 minutes. In economy mode, printers work 20% faster than in normal mode. How many printers are required to print 180 pages in 3 minutes in economy mode?

(C) 2008 GMAT Club - m24#24

* 25
* 28
* 29
* 30
* 32

pgmat · **Posted:** Wed Dec 08, 2010 9:21 am

100 pages in 3 minutes. 20% more in Econ mode means 120 pages in 3 minutes, 20 printers. So, for 180 pages, 3 minutes, it would take 30 printers. So answer is (D)

Posted from my mobile device

mrright · **Posted:** Wed Dec 08, 2010 9:49 am

20 printer, 100 page
1 printer, 5 page
in economy it is 20% faster
so,
1 printer, 5+1 page
==> 180 /6 = 30 printers

vaibhavtripathi · **Posted:** Thu Dec 09, 2010 12:04 am

icandy wrote:

In normal printing mode, 20 printers can print 100 pages in 3 minutes. In economy mode, printers work 20% faster than in normal mode. How many printers are required to print 180 pages in 3 minutes in economy mode?

(A) 25
(B) 28
(C) 29
(D) 30
(E) 32

Normal Printing Mode:
20 Printers, 100 pages, 3 minutes means 1 Printer, 1 Page, \frac{20*3}{100} min.

Economy Mode:
1 Printer, 1 page, \frac{80}{100}*\frac{60}{100} min.
1 Printer, 180 Pages, \frac{180*8*6}{100} min.

If printing must be finished in 3 minutes, number of printers required= \frac{18*8*6}{10}*\frac{1}{3} = 28.8.
Rounding it nearest integer, 29.

Why is that wrong??
Shouldnt "20% Faster" mean "same number of pages in 80% of the time", and not "20% more pages in same duration"??

ruthereyet2010 · **Posted:** Thu Dec 09, 2010 12:06 pm

I have the same thoughts as vaibhavtripathi.

Doesn't faster mean less time and not more pages?

Thanks

jacky13 · **Posted:** Mon Dec 13, 2010 1:44 am

Normal:20 Printers 100Pages 3 min=> 20:100:3
Eco: 20Printers 100Pages+20%100pages 3 mins=>20:120:3
120/20=6pages per printer
so 180 pages need to print means =>180/6 = 30 printer

htskumar · **Posted:** Mon Dec 12, 2011 6:10 am

D.

I had to read the question twice to solve it the simplest way. The 3 mins remains constant which test takers need to identify immediately after reading the que to solve it accurately and quickly.
After looking at the explanation it looks easy. But on the real GMAT we may not solve this in 2 mins if you do not read and understand the question clearly. Good question with multiple variables.

Jdam · **Posted:** Mon Dec 12, 2011 6:32 pm

D

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M24 Q 24

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