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

 It is currently 22 Oct 2018, 10:33

### 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

# MGMAT problem

Author Message
Intern
Joined: 11 Sep 2009
Posts: 17
Location: Tampa ,FL

### Show Tags

22 Sep 2009, 20:09
00:00

Difficulty:

(N/A)

Question Stats:

100% (00:16) correct 0% (00:00) wrong based on 12 sessions

### HideShow timer Statistics

Sam earned a $2000 , commission on a big sale , raising his average commission by$100.If Sam's new average commission is \$900, how many sales has he made?

Ans:
a) 11
b) 12
c) 13

--== Message from the GMAT Club Team ==--

THERE IS LIKELY A BETTER DISCUSSION OF THIS EXACT QUESTION.
This discussion does not meet community quality standards. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
Manager
Joined: 10 Aug 2009
Posts: 129

### Show Tags

22 Sep 2009, 20:24
1
I think 12 sales (including the last one).

X represents the average prior to the last sale and N - the number of sales (NOT including the last sale)
x+100=900
x=800
sum of commissions fron N sales=800N

the average of total sales (oncluding the last one)= $$\frac{800N+2000}{N+1}=900$$
from here, N=11 and N+1=12
Senior Manager
Joined: 31 Aug 2009
Posts: 386
Location: Sydney, Australia

### Show Tags

22 Sep 2009, 23:51
2
Arrived at the same conclusion, slightly diff working but same thing.

Previous Average
1) Sum/N = 800

New Average
2) (Sum+2000) / (N+1) = 900

Subtract equations:
2)-1)
X+2000 = 900N+900
X = 800N
2000 = 100N+900
100N = 1100
N = 11

Manager
Joined: 15 Sep 2009
Posts: 117

### Show Tags

23 Sep 2009, 01:36
I wud go with option 12

800*x + 2000 = 900(x+1)
100x = 1100
x = 11
x+1 = 12
Senior Manager
Joined: 31 Aug 2009
Posts: 386
Location: Sydney, Australia

### Show Tags

23 Sep 2009, 02:03
Sorry, you are correct. Classic case of not reading question stem it is 12 not 11.
Intern
Joined: 11 Sep 2009
Posts: 17
Location: Tampa ,FL

### Show Tags

23 Sep 2009, 07:09
Yes , 12 is the right answer .
Manager
Joined: 27 Oct 2008
Posts: 180

### Show Tags

23 Sep 2009, 11:26
Soln:
New average is 900 for x + 1 items
Earlier average is 800 for x items

eq is
2000 + 800x = 900(x + 1)
solving for x
x = 11

Since the new total is (x + 1) therefore we have total of 12 items sold
Non-Human User
Joined: 09 Sep 2013
Posts: 8535

### Show Tags

21 Nov 2017, 10:31
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.

--== Message from the GMAT Club Team ==--

THERE IS LIKELY A BETTER DISCUSSION OF THIS EXACT QUESTION.
This discussion does not meet community quality standards. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.

_________________
Re: MGMAT problem &nbs [#permalink] 21 Nov 2017, 10:31
Display posts from previous: Sort by