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

It is currently 16 Oct 2019, 00:49

Close

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

In a Physics class of a science course, there are N students

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

Hide Tags

Find Similar Topics 
Retired Moderator
avatar
P
Joined: 22 Aug 2013
Posts: 1430
Location: India
In a Physics class of a science course, there are N students  [#permalink]

Show Tags

New post 26 Mar 2018, 00:41
00:00
A
B
C
D
E

Difficulty:

  75% (hard)

Question Stats:

64% (02:50) correct 36% (02:10) wrong based on 52 sessions

HideShow timer Statistics

In a Physics class of a science course, there are N students present on a particular day. If N is an odd number, is N less than 50?

(1) If 2 more students had been present in the class, they could have been evenly divided in groups of 5 each.

(2) If 3 more students had been present in the class, they could have been evenly divided in groups of 7 each.
examPAL Representative
User avatar
P
Joined: 07 Dec 2017
Posts: 1140
In a Physics class of a science course, there are N students  [#permalink]

Show Tags

New post 26 Mar 2018, 01:47
amanvermagmat wrote:
In a Physics class of a science course, there are N students present on a particular day. If N is an odd number, is N less than 50?

(1) If 2 more students had been present in the class, they could have been evenly divided in groups of 5 each.

(2) If 3 more students had been present in the class, they could have been evenly divided in groups of 7 each.


As we're asked about the max value of N (less than 50?), we'll look at the edge of the range.
This is a Logical appraoch.

(1) So N+2 is divisible by 5, that is, its unit digit is a 0 or a 5. Since N is odd, its unit digit must be a 3.
So any two digit number ending in 3 works. Insufficient.

(2) So N+3 is divisible by 7. Once again, for every even multiple of 7 we can find a value of N. For example, 7*8 - 3 = 53 works as does 7*2 - 3 = 11.
Insufficient.

Combined:
We need to find a number whose unit's digit is 3 and that is 3 less than a multiple of 7. That is, we need to find a multiple of 7 whose units digit is 6. Since the first such multiple of 7 is 56, giving N=56-3=53, then N must be larger than 50. So the answer to our question is NO.

(C) is our answer.
_________________
Manager
Manager
User avatar
B
Joined: 01 Feb 2018
Posts: 73
Location: India
Concentration: Entrepreneurship, Marketing
GPA: 4
WE: Consulting (Consulting)
Re: In a Physics class of a science course, there are N students  [#permalink]

Show Tags

New post 26 Mar 2018, 04:38
amanvermagmat wrote:
In a Physics class of a science course, there are N students present on a particular day. If N is an odd number, is N less than 50?

(1) If 2 more students had been present in the class, they could have been evenly divided in groups of 5 each.

(2) If 3 more students had been present in the class, they could have been evenly divided in groups of 7 each.



considering statement 1

N can be 3, 13, 23, 33, 43 >> not sufficient

considering statement 2
N can be 11, 25, 39 >> not sufficient

now considering 1 & 2 together :
there is no such number less than 50 which can satisfy condition 1 & 2.

Now going back to question :
If N is an odd number, is N less than 50? : NO

answer is C: Both together sufficient .


Kudos if it helps.!!
Intern
Intern
avatar
B
Joined: 05 Mar 2018
Posts: 22
Re: In a Physics class of a science course, there are N students  [#permalink]

Show Tags

New post 27 Mar 2018, 03:07
Oops, think N = 18 and N = 53, the answer is E
Retired Moderator
avatar
P
Joined: 22 Aug 2013
Posts: 1430
Location: India
Re: In a Physics class of a science course, there are N students  [#permalink]

Show Tags

New post 27 Mar 2018, 03:24
colinlin1 wrote:
Oops, think N = 18 and N = 53, the answer is E


Hello

But the question stem says, "..if N is an odd number.." so we will have to discard the value of 18 for N.
Intern
Intern
avatar
B
Joined: 05 Mar 2018
Posts: 22
Re: In a Physics class of a science course, there are N students  [#permalink]

Show Tags

New post 27 Mar 2018, 17:44
amanvermagmat wrote:
colinlin1 wrote:
Oops, think N = 18 and N = 53, the answer is E


Hello

But the question stem says, "..if N is an odd number.." so we will have to discard the value of 18 for N.

Thank you, you are right.
GMAT Club Bot
Re: In a Physics class of a science course, there are N students   [#permalink] 27 Mar 2018, 17:44
Display posts from previous: Sort by

In a Physics class of a science course, there are N students

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





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