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

It is currently 27 Jun 2019, 03:48

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

On a certain multiple-choice test, 9 points are awarded for each corre

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

Hide Tags

 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 55804
On a certain multiple-choice test, 9 points are awarded for each corre  [#permalink]

Show Tags

New post 26 Oct 2016, 06:47
1
3
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

72% (01:59) correct 28% (02:09) wrong based on 151 sessions

HideShow timer Statistics


On a certain multiple-choice test, 9 points are awarded for each correct answer, and 7 points are deducted for each incorrect or unanswered question. Sally received a total score of 0 points on the test. If the test has fewer than 30 questions, how many questions are on the test?

A. Cannot be determined
B. 16
C. 19
D. 21
E. 24

_________________
Intern
Intern
avatar
B
Joined: 17 Aug 2016
Posts: 48
Re: On a certain multiple-choice test, 9 points are awarded for each corre  [#permalink]

Show Tags

New post 26 Oct 2016, 07:17
1
9x - 7y = 0
x = 7/9 y --> y needs to be a multiple of 9 i.e 9, 18, 27 etc if y=9 x=7 if y=18 x=14 (18+14>30) therefore answer is 9+7 = 16 (B)
Intern
Intern
avatar
Joined: 17 Apr 2016
Posts: 4
Re: On a certain multiple-choice test, 9 points are awarded for each corre  [#permalink]

Show Tags

New post 26 Oct 2016, 08:21
Let x be no. of correct questions and y be no. of incorrect or unaswered question.
9x-7y=0
9(7)-7(9)=0
therefore total number of questions on test =7+9=16
Ans:16

I hope i'm right.

Sent from my SM-G130H using GMAT Club Forum mobile app
Current Student
avatar
B
Joined: 26 Jan 2016
Posts: 100
Location: United States
GPA: 3.37
Re: On a certain multiple-choice test, 9 points are awarded for each corre  [#permalink]

Show Tags

New post 26 Oct 2016, 10:22
1
The LCM of 7 and 9 is 63. In order to get a score of 0 she needs to get 7 question right (63 points) and 9 questions wrong (-63 points) to get a score of 0. 9+7=16
Manager
Manager
avatar
Joined: 29 Aug 2008
Posts: 106
Re: On a certain multiple-choice test, 9 points are awarded for each corre  [#permalink]

Show Tags

New post 26 Oct 2016, 10:24
1
9x - 7y = 0

x + y < 30

9x = 7y

Y = 9x/7

So x has to be a multiple of 7 (7, 14, 21.....)

if X = 7 we get y =9 and the total no of questions as 16.

If we take x = 14, we get Y = 18 and total no of questions as 32, whereas we have been told that they are less than 30.

So 16 is the answer.

Option B.
Manager
Manager
avatar
Joined: 17 Nov 2013
Posts: 80
GMAT ToolKit User
Re: On a certain multiple-choice test, 9 points are awarded for each corre  [#permalink]

Show Tags

New post 24 Nov 2016, 08:58
1
9c - 7i = 0
9c = 7i
c = 7i/9

i = 9, 18, 27
c = 7, 14, 21

t = 16, 32, 48

answer is B
VP
VP
User avatar
P
Joined: 31 Oct 2013
Posts: 1376
Concentration: Accounting, Finance
GPA: 3.68
WE: Analyst (Accounting)
Re: On a certain multiple-choice test, 9 points are awarded for each corre  [#permalink]

Show Tags

New post 18 Jul 2018, 15:33
Bunuel wrote:
On a certain multiple-choice test, 9 points are awarded for each correct answer, and 7 points are deducted for each incorrect or unanswered question. Sally received a total score of 0 points on the test. If the test has fewer than 30 questions, how many questions are on the test?

A. Cannot be determined
B. 16
C. 19
D. 21
E. 24



Let the number of correct question be x

and the number of incorrect question be y.

Note : As final result is 0, it's clear that marks from correct answer and the marks from incorrect answer were same.

So,

9x = 7y

x/y = 7 / 9

( x + y ) = 16 or the multiple of 16.

As total question is less than 30, it's clear that total number of questions was 16.

The best answer is B.
e-GMAT Representative
User avatar
D
Joined: 04 Jan 2015
Posts: 2911
Re: On a certain multiple-choice test, 9 points are awarded for each corre  [#permalink]

Show Tags

New post 19 Jul 2018, 06:02

Solution



Given:
• In the test, 9 points are awarded for each correct answer.
• Else, 7 points are deducted
• Sally received a total score of 0 points on the test
• The test has fewer than 30 questions

Approach and Working:
Let, the correct question be x and rest questions be y.
Hence, 9x-7y=0
• x=7, y=9, x+y= 16
• x= 14, y= 18 , x+y= 32
• and more..
• But, there is only one possible value of x and y such that x+y is less than 30.
Hence, the correct answer is option B.

Answer: B
_________________
Intern
Intern
User avatar
B
Status: No Progress without Struggle
Joined: 04 Aug 2017
Posts: 42
Location: Armenia
GPA: 3.4
Re: On a certain multiple-choice test, 9 points are awarded for each corre  [#permalink]

Show Tags

New post 29 Jul 2018, 07:57
We should firstly write an appropriate equation. Let's assign r for the number of right questions and w for the number of wrong questions.
So, 9r-7w=0
9r=7w
w=9r/7
So, r has to be a multiple of 7.
From the multiples of 7, only 7 satisfies the equation since the number of questions should not surpass 30.
7+9=16
_________________
Seryozha Sargsyan 21

Contact: sargsyanseryozha@gmail.com

What you think, you become,
What you feel, you attract,
What you imagine, you create.
Intern
Intern
avatar
Joined: 30 Aug 2018
Posts: 1
Re: On a certain multiple-choice test, 9 points are awarded for each corre  [#permalink]

Show Tags

New post 16 Sep 2018, 00:51
No test will give you result in negative. You either score a zero or more. So, even if the girl has written every answer wrongly - the score would be still 0. 16 is another possibility. So the answer should be CAN'T BE DETERMINED right? How is it selected as 16?
GMAT Club Bot
Re: On a certain multiple-choice test, 9 points are awarded for each corre   [#permalink] 16 Sep 2018, 00:51
Display posts from previous: Sort by

On a certain multiple-choice test, 9 points are awarded for each corre

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


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