Last visit was: 25 Jul 2024, 09:53 It is currently 25 Jul 2024, 09:53
Toolkit
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.

# For the past n days, the average (arithmetic mean) daily

SORT BY:
Tags:
Show Tags
Hide Tags
Intern
Joined: 01 Apr 2012
Posts: 13
Own Kudos [?]: 1 [0]
Given Kudos: 138
Manager
Joined: 31 Jul 2017
Posts: 167
Own Kudos [?]: 335 [0]
Given Kudos: 347
Location: Tajikistan
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 10133
Own Kudos [?]: 17062 [1]
Given Kudos: 4
GMAT 1: 760 Q51 V42
GPA: 3.82
Director
Joined: 14 Jul 2010
Status:No dream is too large, no dreamer is too small
Posts: 958
Own Kudos [?]: 5019 [0]
Given Kudos: 690
Concentration: Accounting
Re: For the past n days, the average (arithmetic mean) daily [#permalink]
Top Contributor
Abhishek009 wrote:
For the past n days, the average (arithmetic mean) daily production at a company was 50 units. If today's production of 90 units raises the average to 55 units per day, what is the value of n ?

(A) 30
(B) 18
(C) 10
(D) 9
(E) 7

$$\frac{50n + 90}{n + 1}= 55$$

$$50n + 90 = 55n + 55$$

$$5n = 45$$

So, $$n = 9$$

Thus, answer must be (D) 9

$$55(n+1)-50n=90$$

$$⇒ 55n+55-50n=90$$

$$⇒ 5n=35$$

$$∴ n=7$$

The answer E, Do you may have a typo.
Director
Joined: 14 Jul 2010
Status:No dream is too large, no dreamer is too small
Posts: 958
Own Kudos [?]: 5019 [0]
Given Kudos: 690
Concentration: Accounting
Re: For the past n days, the average (arithmetic mean) daily [#permalink]
Top Contributor
For the past n days, the average (arithmetic mean) daily production at a company was 50 units. If today's production of 90 units raises the average to 55 units per day, what is the value of n ?

(A) 30
(B) 18
(C) 10
(D) 9
(E) 7

The average is 50, the additional units have to be divided among the total people as the average increased.

The additional units beyond average 90-50=40

So, $$\frac{40}{n+1}=5$$
$$⇒ 5n+5=40$$
$$⇒ 5n=35$$
$$⇒n=7$$

Director
Joined: 04 Jun 2020
Posts: 542
Own Kudos [?]: 74 [0]
Given Kudos: 623
Re: For the past n days, the average (arithmetic mean) daily [#permalink]
avigutman wrote:
Video solution from Quant Reasoning:
Subscribe for more: https://www.youtube.com/QuantReasoning? ... irmation=1

avigutman

Thank you! Perhaps I am reading into this too much, but how do we necessarily know that there are not any days in between the "past n days" and today? What if there was break?
Tutor
Joined: 17 Jul 2019
Posts: 1304
Own Kudos [?]: 1750 [0]
Given Kudos: 66
GMAT 1: 780 Q51 V45
GMAT 2: 780 Q50 V47
GMAT 3: 770 Q50 V45
Re: For the past n days, the average (arithmetic mean) daily [#permalink]
woohoo921 wrote:
Perhaps I am reading into this too much, but how do we necessarily know that there are not any days in between the "past n days" and today? What if there was break?

Does this help, woohoo921?
https://www.gymglish.com/en/gymglish/en ... seven-days

Posted from my mobile device
Director
Joined: 04 Jun 2020
Posts: 542
Own Kudos [?]: 74 [0]
Given Kudos: 623
Re: For the past n days, the average (arithmetic mean) daily [#permalink]
avigutman wrote:
woohoo921 wrote:
Perhaps I am reading into this too much, but how do we necessarily know that there are not any days in between the "past n days" and today? What if there was break?

Does this help, woohoo921?
https://www.gymglish.com/en/gymglish/en ... seven-days

Posted from my mobile device

avigutman
Thank you for your quick response. As a general rule, when the GMAT says "past few days" does that just always mean a few days prior until now?
Tutor
Joined: 17 Jul 2019
Posts: 1304
Own Kudos [?]: 1750 [1]
Given Kudos: 66
GMAT 1: 780 Q51 V45
GMAT 2: 780 Q50 V47
GMAT 3: 770 Q50 V45
Re: For the past n days, the average (arithmetic mean) daily [#permalink]
1
Kudos
woohoo921 wrote:
avigutman wrote:
woohoo921 wrote:
Perhaps I am reading into this too much, but how do we necessarily know that there are not any days in between the "past n days" and today? What if there was break?

Does this help, woohoo921?
https://www.gymglish.com/en/gymglish/en ... seven-days

As a general rule, when the GMAT says "past few days" does that just always mean a few days prior until now?

Yes, woohoo921. And that rule isn't limited to the GMAT.
Non-Human User
Joined: 09 Sep 2013
Posts: 34093
Own Kudos [?]: 853 [0]
Given Kudos: 0
Re: For the past n days, the average (arithmetic mean) daily [#permalink]
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.
Re: For the past n days, the average (arithmetic mean) daily [#permalink]
1   2
Moderator:
Math Expert
94616 posts