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

 It is currently 14 Dec 2019, 10:52

### 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
Your Progress

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

# 240 students are to be arranged in n rows in the assembly hall

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

### Hide Tags

Director
Joined: 18 Feb 2019
Posts: 607
Location: India
GMAT 1: 460 Q42 V13
GPA: 3.6
240 students are to be arranged in n rows in the assembly hall  [#permalink]

### Show Tags

14 Mar 2019, 06:14
5
00:00

Difficulty:

45% (medium)

Question Stats:

64% (01:50) correct 36% (02:28) wrong based on 59 sessions

### HideShow timer Statistics

240 students are to be arranged in n rows in the assembly hall of a school. If the first row is the closest to the stage and each subsequent row has 10 more students than the row ahead of it, what is the value of n?

I. There are 45 students in the 4th row from the stage.
II. The number of students in the nth row is 10 less than 5 times the number of students in the first row.
GMAT Club Legend
Joined: 18 Aug 2017
Posts: 5483
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)
Re: 240 students are to be arranged in n rows in the assembly hall  [#permalink]

### Show Tags

19 Mar 2019, 12:35
kiran120680 wrote:
240 students are to be arranged in n rows in the assembly hall of a school. If the first row is the closest to the stage and each subsequent row has 10 more students than the row ahead of it, what is the value of n?

I. There are 45 students in the 4th row from the stage.
II. The number of students in the nth row is 10 less than 5 times the number of students in the first row.

I am not sure how answer is D
IMO A is sufficinet
#2
i am not able to make the relation as its given
Director
Joined: 28 Jul 2016
Posts: 679
Location: India
Concentration: Finance, Human Resources
GPA: 3.97
WE: Project Management (Investment Banking)
Re: 240 students are to be arranged in n rows in the assembly hall  [#permalink]

### Show Tags

19 Mar 2019, 21:15
1
Answer : D
Explanation:
Le the number of students in row 1 =a
I : A.P question 45 students in 4th row = a+3*10 = 45 . thus a=15
Total students = 240 hence
$$\frac{n}{2}(2a+(n-1)d)= 240$$
Solve for n . Hence sufficient

II: Students in last row(nth row) = a+(n-1)d
given a+(n-1)d +10 = 5a
solve the above equation:
4a= 10n
thus a= 5/2 n

Now as per A.P sum
$$\frac{n}{2}(2a+(n-1)d)= 240$$
substitute value of a
and simplify the equation
$$\frac{25n^2}{4}=850$$
thus n = 12
Hence II is also sufficient
Thus answer D
Re: 240 students are to be arranged in n rows in the assembly hall   [#permalink] 19 Mar 2019, 21:15
Display posts from previous: Sort by

# 240 students are to be arranged in n rows in the assembly hall

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne