It is currently 22 Feb 2018, 08:54

# TODAY:

MIT Sloan Releasing 1st Wave of Interview Invites - Join GMATClub CHAT for Live Updates

### 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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# In an engineering class that contains 50 students, the final exam

Author Message
TAGS:

### Hide Tags

Intern
Joined: 05 Aug 2015
Posts: 5
In an engineering class that contains 50 students, the final exam [#permalink]

### Show Tags

14 May 2016, 05:08
2
This post was
BOOKMARKED
00:00

Difficulty:

15% (low)

Question Stats:

80% (01:44) correct 20% (02:19) wrong based on 70 sessions

### HideShow timer Statistics

In an engineering class that contained 50 students, the final exam consisted of 2 questions. Three fifths of the students answered the first question correctly. If four fifths of the remainder answered the second question correctly, how many students answered both questions incorrectly?

A) 4
B) 6
C) 10
D) 12
E) 24

I thought the answer was E but it's not. Can anybody give me a detailed explanation of the solution please?
[Reveal] Spoiler: OA
Math Expert
Joined: 02 Aug 2009
Posts: 5660
In an engineering class that contains 50 students, the final exam [#permalink]

### Show Tags

14 May 2016, 06:33
1
KUDOS
Expert's post
mmch wrote:
In an engineering class that contained 50 students, the final exam consisted of 2 questions. Three fifths of the students answered the first question correctly. If four fifths of the remainder answered the second question correctly, how many students answered both questions incorrectly?

A) 4
B) 6
C) 10
D) 12
E) 24

I thought the answer was E but it's not. Can anybody give me a detailed explanation of the solution please?

Hi,
we are looking for students who answered BOTH Qs incorrectly..
1st Question : Three fifths of the students answered the first question correctly - so $$\frac{3}{5} *50 = 30$$
2nd Question : four fifths of the remainder answered the second question correctly so $$\frac{4}{5}* (50-30) = \frac{4}{5} * 20 = 16$$..
total students who answered atleast one Q correct =$$30+16 = 46$$..
so students who answered BOTH incorrectly = $$50-46 = 4$$
A
_________________

Absolute modulus :http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html

BANGALORE/-

Board of Directors
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 3326
Location: India
GPA: 3.5
Re: In an engineering class that contains 50 students, the final exam [#permalink]

### Show Tags

14 May 2016, 06:48
1
KUDOS
Answer will definitely be (A) as chetan2u has shown here is the grid approach ( in case you find it useful )
Attachment:

GRID.PNG [ 3.92 KiB | Viewed 879 times ]

_________________

Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )

Intern
Joined: 05 Aug 2015
Posts: 5
Re: In an engineering class that contains 50 students, the final exam [#permalink]

### Show Tags

14 May 2016, 07:00
Thank you guys! The explanation helped a lot!
Manager
Joined: 19 Aug 2016
Posts: 150
Location: India
GMAT 1: 640 Q47 V31
GPA: 3.82
Re: In an engineering class that contains 50 students, the final exam [#permalink]

### Show Tags

25 Apr 2017, 01:11
mmch wrote:
In an engineering class that contained 50 students, the final exam consisted of 2 questions. Three fifths of the students answered the first question correctly. If four fifths of the remainder answered the second question correctly, how many students answered both questions incorrectly?

A) 4
B) 6
C) 10
D) 12
E) 24

I thought the answer was E but it's not. Can anybody give me a detailed explanation of the solution please?

Total number of students: 50

No. of students who answered the 1st question correctly: 3/5 of 50 =30
No. of students who answered the 2nd question correctly: 4/5 of remaining i.e. 20 = 16.

Since, the students have to answer the questions and 46 of them answered at least one of them correctly, therefore students who have answered both incorrectly would be 50-46 = 4.

_________________

Consider giving me Kudos if you find my posts useful, challenging and helpful!

Re: In an engineering class that contains 50 students, the final exam   [#permalink] 25 Apr 2017, 01:11
Display posts from previous: Sort by

# In an engineering class that contains 50 students, the final exam

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.