Summer is Coming! Join the Game of Timers Competition to Win Epic Prizes. Registration is Open. Game starts Mon July 1st.

 It is currently 21 Jul 2019, 06:29 ### 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

#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.  # During the first week in May, a video salesman sold n videos at an ave

Author Message
TAGS:

### Hide Tags

Math Expert V
Joined: 02 Sep 2009
Posts: 56307
During the first week in May, a video salesman sold n videos at an ave  [#permalink]

### Show Tags 00:00

Difficulty:   15% (low)

Question Stats: 91% (01:51) correct 9% (00:47) wrong based on 30 sessions

### HideShow timer Statistics During the first week in May, a video salesman sold n videos at an average (arithmetic mean) commission of z dollars per video. During the next week, the same salesman sold n – 4 videos at an average commission of $15 less than the week before. What is the difference in total commissions from the first week to the second week in terms of n and z? A. nz – 60 B. n^2 – z + 60 C. 2nz – 15z +60 D. 4z + 15n – 60 E. 4z + 60 _________________ Intern  B Joined: 28 May 2017 Posts: 9 Location: India Concentration: Finance, General Management GPA: 3.85 WE: Programming (Computer Software) Re: During the first week in May, a video salesman sold n videos at an ave [#permalink] ### Show Tags I solved this by trial and error method Lets say that first week the salesman sells 10 videos at 35$ commission.
first week = 350$commission second week 6 videos at 20$ commission
second week = 120$commission difference = 350 - 120 = 230$

we took n = 10 and z = 35

Try to check with all the options

the correct answer is D (4*35 + 15*10 - 60 = 230)
Senior SC Moderator V
Joined: 22 May 2016
Posts: 3094
During the first week in May, a video salesman sold n videos at an ave  [#permalink]

### Show Tags

Bunuel wrote:
During the first week in May, a video salesman sold n videos at an average (arithmetic mean) commission of z dollars per video. During the next week, the same salesman sold n – 4 videos at an average commission of $15 less than the week before. What is the difference in total commissions from the first week to the second week in terms of n and z? A. nz – 60 B. n^2 – z + 60 C. 2nz – 15z +60 D. 4z + 15n – 60 E. 4z + 60 Attachment: AnScommissions.png [ 17.5 KiB | Viewed 583 times ] Algebra $$A*n = S$$ • Week 1 A = z n = n SUM = nz • Week 2 A = (z - 15) n = (n - 4) SUM = (n - 4)(z - 15) For Week 2 SUM, multiply terms A*n (n - 4)(z - 15) SUM = (nz - 25n - 4z + 60) • DIFFERENCE between Week 1 SUM and Week 2 SUM? nz - (nz - 25n - 4z + 60) = nz - nz + 25n + 4z - 60 = 25n + 4z - 60, or 4z + 25n - 60 Answer D Assign values Let Week 1 number of videos sold, n = 6 Let Week 1 average price of video, z =$20
Week 2 number of videos sold is (n-4), n = 2
Week 2 average price per video is (z-15), ($20 - 15) = z =$5

• Week 1 SUM, where A*n = S
($20 * 6) =$120

• Week 2 SUM
($5 * 2) =$10

• Difference between Week 1 sum and Week 2 sum:
$120 - 10 =$110

Using n = 6, z = 20, find the answer choice that yields 110

A) nz – 60
120 - 60 = $60. NOT A MATCH B) n^2 – z + 60 36 - 20 + 60 = 76. NOT A MATCH C) 2nz – 15z +60 2(120) - (15)(20) + 60 240 - 300 + 60 = 0. NOT A MATCH D) 4z + 15n – 60 80 + 90 - 60 = 110. MATCH E) 4z + 60 80 + 60 = 140. NOT A MATCH Answer D _________________ SC Butler has resumed! Get two SC questions to practice, whose links you can find by date, here. -- Take another look. Take a look around. These are the moments you can't pass by. Intern  B Joined: 28 Oct 2015 Posts: 15 During the first week in May, a video salesman sold n videos at an ave [#permalink] ### Show Tags I got D answer by taking sample values and then poe. Is there any easy way please for this Bunuel Sent from my iPhone using GMAT Club Forum Intern  B Joined: 16 Jan 2018 Posts: 13 Re: During the first week in May, a video salesman sold n videos at an ave [#permalink] ### Show Tags generis wrote: Bunuel wrote: During the first week in May, a video salesman sold n videos at an average (arithmetic mean) commission of z dollars per video. During the next week, the same salesman sold n – 4 videos at an average commission of$15 less than the week before. What is the difference in total commissions from the first week to the second week in terms of n and z?

A. nz – 60
B. n^2 – z + 60
C. 2nz – 15z +60
D. 4z + 15n – 60
E. 4z + 60

Attachment:
AnScommissions.png

Algebra
$$A*n = S$$

• Week 1
A = z
n = n
SUM = nz

• Week 2
A = (z - 15)
n = (n - 4)
SUM = (n - 4)(z - 15)

For Week 2 SUM, multiply terms A*n
(n - 4)(z - 15)
SUM = (nz - 25n - 4z + 60)

• DIFFERENCE between Week 1 SUM and Week 2 SUM?
nz - (nz - 25n - 4z + 60) =
nz - nz + 25n + 4z - 60 =
25n + 4z - 60, or
4z + 25n - 60

Assign values

Let Week 1 number of videos sold, n = 6
Let Week 1 average price of video, z = $20 Week 2 number of videos sold is (n-4), n = 2 Week 2 average price per video is (z-15), ($20 - 15) = z = $5 • Week 1 SUM, where A*n = S ($20 * 6) = $120 • Week 2 SUM ($5 * 2) = $10 • Difference between Week 1 sum and Week 2 sum:$120 - 10 = $110 Using n = 6, z = 20, find the answer choice that yields 110 A) nz – 60 120 - 60 =$60. NOT A MATCH

B) n^2 – z + 60
36 - 20 + 60 = 76. NOT A MATCH

C) 2nz – 15z +60
2(120) - (15)(20) + 60
240 - 300 + 60 = 0. NOT A MATCH

D) 4z + 15n – 60
80 + 90 - 60 = 110. MATCH

E) 4z + 60
80 + 60 = 140. NOT A MATCH

Hi,

For Week 2 SUM, multiply terms A*n
(n - 4)(z - 15)
SUM = (nz - 25n - 4z + 60)

Thanks Re: During the first week in May, a video salesman sold n videos at an ave   [#permalink] 12 Aug 2018, 23:39
Display posts from previous: Sort by

# During the first week in May, a video salesman sold n videos at an ave  