GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 15 Oct 2018, 03:42

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# M08-10

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 49965

### Show Tags

16 Sep 2014, 00:36
00:00

Difficulty:

65% (hard)

Question Stats:

59% (01:33) correct 41% (02:05) wrong based on 78 sessions

Machine A can produce 50 components a day while Machine B only 40. The monthly maintenance cost for Machine A is $1500 while the cost for Machine B is$550. If each component generates an income of $10, what is the least number of days per month that the plant has to operate to justify the usage of Machine A instead of Machine B? A. 6 B. 7 C. 9 D. 10 E. 11 _________________ Math Expert Joined: 02 Sep 2009 Posts: 49965 Re M08-10 [#permalink] ### Show Tags 16 Sep 2014, 00:37 1 Official Solution: Machine A can produce 50 components a day while Machine B only 40. The monthly maintenance cost for Machine A is$1500 while the cost for Machine B is $550. If each component generates an income of$10, what is the least number of days per month that the plant has to operate to justify the usage of Machine A instead of Machine B?

A. 6
B. 7
C. 9
D. 10
E. 11

Monthly maintenance costs for machine A and for machine B are fixed. Meaning that even if the plant doesn't operate at all it'll still have these maintenance costs. The questions basically asks about minimum # of days (d) that plant should operate so that the profit from A is more than or equal to the profit from B.

Profit from machine A in d days: $$50*10*d-1,500$$;

Profit from machine B in d days: $$40*10*d-550$$;

$$50*10*d-1,500 \ge 40*10*d-550$$, which leads to $$d \ge 9.5$$. Hence the minimum # of days is 10.

_________________
Intern
Joined: 22 Aug 2014
Posts: 44

### Show Tags

19 Jan 2016, 06:54
Cover up the higher fixed cost, machine A needs to operate for at least a number days . But what is the number of days?
Profit=revenue -cost=price*quantity-cost
here only fixed cost counts.
profit for A=10*quantity-1500=10*50*d-1500
profit for B=10*40*d-550
10*50*d-1500≥10*40*d-550
or,d≥9.5
so, 9.5 or higher gives us 10 days.
Intern
Joined: 03 Jul 2015
Posts: 29

### Show Tags

19 Jan 2016, 11:07
1
attached
>> !!!

You do not have the required permissions to view the files attached to this post.

Intern
Joined: 05 Jan 2015
Posts: 9

### Show Tags

19 Jan 2016, 19:05
Monthly maintenance cost for A is 950$more than for B. But every day A generates 100$ more income than B.
Then A needs to run at least 950/100 = 9.5 (rounded to 10) days to cover the difference in maintenance cost.

Bunuel wrote:
Machine A can produce 50 components a day while Machine B only 40. The monthly maintenance cost for Machine A is $1500 while the cost for Machine B is$550. If each component generates an income of $10, what is the least number of days per month that the plant has to operate to justify the usage of Machine A instead of Machine B? A. 6 B. 7 C. 9 D. 10 E. 11 Intern Joined: 03 Aug 2018 Posts: 2 Re: M08-10 [#permalink] ### Show Tags 13 Aug 2018, 11:41 "If each component generates an income of$10, what is the least number of days per month that the plant has to operate to justify the usage of Machine A instead of Machine B?"

This is a poor quality question, as the number of days requested is unclear. The question would be MUCH clearer if read:

"If each component generates an income of \$10, what is the least number of additionaldays per month that the plant would have to operate to justify the usage of Machine A instead of Machine B?"
Senior Manager
Joined: 12 Feb 2015
Posts: 481

### Show Tags

01 Oct 2018, 23:16
With this post I want to explain exactly what is happening in this question:-

Attachment:
Mac A vs B.jpg

The blue line (profit for machine A) is above the orange line (profit for machine B) after 10 days (approx)

Attachment:
Mac A vs B (2).jpg

>> !!!

You do not have the required permissions to view the files attached to this post.

_________________

"Please hit +1 Kudos if you like this post"

_________________
Manish

"Only I can change my life. No one can do it for me"

Re: M08-10 &nbs [#permalink] 01 Oct 2018, 23:16
Display posts from previous: Sort by

# M08-10

Moderators: chetan2u, Bunuel

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.