Author 
Message 
TAGS:

Hide Tags

Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4664

At Mnemosyne Middle School, there are 700 students: all the students a
[#permalink]
Show Tags
28 Feb 2017, 12:25
Question Stats:
57% (03:20) correct 43% (03:15) wrong based on 154 sessions
HideShow timer Statistics
At Mnemosyne Middle School, there are 700 students: all the students are boys or girls in the 4th or 5th grade. There are 320 students in the 4th grade, and there are 210 girls in the 5th grade. Fifty percent of the 5th graders and 40% of the 4th graders take Mandarin Chinese. Ninety 5th grade boys do not take Mandarin Chinese. The number of 4th grade girls taking Mandarin Chinese is less than half of the number of 5th grade girls taking Mandarin Chinese. Which of the following could be the number of 4th grade boys in Mandarin Chinese?
(A) 10 (B) 40 (C) 70 (D) 100 (E) 130This is one of a set of fifteen challenging GMAT Quant problems. To see the whole collection, as well as the OE for this question, go to: Challenging GMAT Math Practice QuestionsMike
Official Answer and Stats are available only to registered users. Register/ Login.
_________________
Mike McGarry Magoosh Test Prep
Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)





Math Expert
Joined: 02 Aug 2009
Posts: 6791

Re: At Mnemosyne Middle School, there are 700 students: all the students a
[#permalink]
Show Tags
02 Mar 2017, 06:55
mikemcgarry wrote: At Mnemosyne Middle School, there are 700 students: all the students are boys or girls in the 4th or 5th grade. There are 320 students in the 4th grade, and there are 210 girls in the 5th grade. Fifty percent of the 5th graders and 40% of the 4th graders take Mandarin Chinese. Ninety 5th grade boys do not take Mandarin Chinese. The number of 4th grade girls taking Mandarin Chinese is less than half of the number of 5th grade girls taking Mandarin Chinese. Which of the following could be the number of 5th grade boys in Mandarin Chinese?
(A) 10 (B) 40 (C) 70 (D) 100 (E) 130This is one of a set of fifteen challenging GMAT Quant problems. To see the whole collection, as well as the OE for this question, go to: Challenging GMAT Math Practice QuestionsMike Hi A point.. Either the Q has some typo error or it contains unnecessary info and wrong choicesAt Mnemosyne Middle School, there are 700 students: all the students are boys or girls in the 4th or 5th grade. There are 320 students in the 4th grade  So 5th grade has 700320=380 students, and there are 210 girls in the 5th grade.  So total boys in 5th grade are 380210=170 Fifty percent of the 5th graders and 40% of the 4th graders take Mandarin Chinese.  In present scenario, nothing comes out of this Ninety 5th grade boys do not take Mandarin Chinese.  So remaining read mandarin Chinese. That is 17090=80 The number of 4th grade girls taking Mandarin Chinese is less than half of the number of 5th grade girls taking Mandarin Chinese.  Not required Which of the following could be the number of 5th grade boys in Mandarin Chinese? We have already found it as 80.. 80 is not in ANSWER ???
_________________
1) Absolute modulus : http://gmatclub.com/forum/absolutemodulusabetterunderstanding210849.html#p1622372 2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html 3) effects of arithmetic operations : https://gmatclub.com/forum/effectsofarithmeticoperationsonfractions269413.html
GMAT online Tutor



Manager
Joined: 28 Jul 2016
Posts: 135

Re: At Mnemosyne Middle School, there are 700 students: all the students a
[#permalink]
Show Tags
02 Mar 2017, 07:42
According to OA from Magoosh website  answer is about 4th grade boys taking Mandarin Chinese, not 5th... https://magoosh.com/gmat/2017/challengi ... questions/



Intern
Joined: 28 Jul 2011
Posts: 30
Location: United Kingdom
WE: Corporate Finance (Energy and Utilities)

Re: At Mnemosyne Middle School, there are 700 students: all the students a
[#permalink]
Show Tags
02 Mar 2017, 08:01
Is the answer 100? (D)
Attachments
Capture.PNG [ 12.36 KiB  Viewed 2247 times ]



Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4664

Re: At Mnemosyne Middle School, there are 700 students: all the students a
[#permalink]
Show Tags
02 Mar 2017, 11:08
chetan2u wrote: mikemcgarry wrote: At Mnemosyne Middle School, there are 700 students: all the students are boys or girls in the 4th or 5th grade. There are 320 students in the 4th grade, and there are 210 girls in the 5th grade. Fifty percent of the 5th graders and 40% of the 4th graders take Mandarin Chinese. Ninety 5th grade boys do not take Mandarin Chinese. The number of 4th grade girls taking Mandarin Chinese is less than half of the number of 5th grade girls taking Mandarin Chinese. Which of the following could be the number of 5th grade boys in Mandarin Chinese?
(A) 10 (B) 40 (C) 70 (D) 100 (E) 130This is one of a set of fifteen challenging GMAT Quant problems. To see the whole collection, as well as the OE for this question, go to: Challenging GMAT Math Practice QuestionsMike Hi A point.. Either the Q has some typo error or it contains unnecessary info and wrong choicesLeonidK wrote: According to OA from Magoosh website  answer is about 4th grade boys taking Mandarin Chinese, not 5th... Dear chetan2u & LeonidK, Thank you very much to both of you! Yes, these tiny typos sometimes are the hardest things to find and notice. Indeed, the prompt question was supposed to be about the number of 4th grade boys in Mandarin. I corrected the question above and the blog. Thank you very much for finding this typo! Mike McGarry
_________________
Mike McGarry Magoosh Test Prep
Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)



Manager
Status: Profile 1
Joined: 20 Sep 2015
Posts: 68
GPA: 3.2
WE: Information Technology (Investment Banking)

Re: At Mnemosyne Middle School, there are 700 students: all the students a
[#permalink]
Show Tags
21 Apr 2017, 11:30
At Mnemosyne Middle School, there are 700 students: all the students are boys or girls in the 4th or 5th grade. There are 320 students in the 4th grade, and there are 210 girls in the 5th grade. Fifty percent of the 5th graders and 40% of the 4th graders take Mandarin Chinese. Ninety 5th grade boys do not take Mandarin Chinese. The number of 4th grade girls taking Mandarin Chinese is less than half of the number of 5th grade girls taking Mandarin Chinese. Which of the following could be the number of 4th grade boys in Mandarin Chinese?
(A) 10 (B) 40 (C) 70 (D) 100 (E) 130
with all the corrections given above in the question...
210 Girls in 5th & 90 Boys in 5th do not take bla bla... = 5th grade is having mix of Girls and Boys
The number of 4th grade girls taking Mandarin Chinese is less than half bla bla..(less than half could be 0) + all the students are boys or girls in the 4th or 5th grade + question asked for number of boys in 4th grade (non zero ans option so) = 4th grade is having only Boys (320 Boys) 40% of the 4th graders take Mandarin Chinese + number of 4th grade boys in Mandarin Chinese = 320*(4/10) =128
please correct me...



Director
Joined: 05 Mar 2015
Posts: 984

Re: At Mnemosyne Middle School, there are 700 students: all the students a
[#permalink]
Show Tags
27 Apr 2017, 08:11
mikemcgarry wrote: chetan2u wrote: mikemcgarry wrote: At Mnemosyne Middle School, there are 700 students: all the students are boys or girls in the 4th or 5th grade. There are 320 students in the 4th grade, and there are 210 girls in the 5th grade. Fifty percent of the 5th graders and 40% of the 4th graders take Mandarin Chinese. Ninety 5th grade boys do not take Mandarin Chinese. The number of 4th grade girls taking Mandarin Chinese is less than half of the number of 5th grade girls taking Mandarin Chinese. Which of the following could be the number of 5th grade boys in Mandarin Chinese?
(A) 10 (B) 40 (C) 70 (D) 100 (E) 130This is one of a set of fifteen challenging GMAT Quant problems. To see the whole collection, as well as the OE for this question, go to: Challenging GMAT Math Practice QuestionsMike Hi A point.. Either the Q has some typo error or it contains unnecessary info and wrong choicesLeonidK wrote: According to OA from Magoosh website  answer is about 4th grade boys taking Mandarin Chinese, not 5th... Dear chetan2u & LeonidK, Thank you very much to both of you! Yes, these tiny typos sometimes are the hardest things to find and notice. Indeed, the prompt question was supposed to be about the number of 4th grade boys in Mandarin. I corrected the question above and the blog. Thank you very much for finding this typo! Mike McGarry mikemcgarryPlease make above question correct as said earlier thanks



Senior CR Moderator
Status: Long way to go!
Joined: 10 Oct 2016
Posts: 1387
Location: Viet Nam

Re: At Mnemosyne Middle School, there are 700 students: all the students a
[#permalink]
Show Tags
27 Apr 2017, 08:56
The correct question written on blog as below. mikemcgarry: Please make sure your question correct. Quote: At Mnemosyne Middle School, there are 700 students: all the students are boys or girls in the 4th or 5th grade. There are 320 students in the 4th grade, and there are 210 girls in the 5th grade. Fifty percent of the 5th graders and 40% of the 4th graders take Mandarin Chinese. Ninety 5th grade boys do not take Mandarin Chinese. The number of 4th grade girls taking Mandarin Chinese is less than half of the number of 5th grade girls taking Mandarin Chinese. Which of the following could be the number of 4th grade boys in Mandarin Chinese?
(A) 10 (B) 40 (C) 70 (D) 100 (E) 130 Here is the table I've made for easier view. Attachment:
Table.PNG [ 4.47 KiB  Viewed 1821 times ]
First, there are 320 4th grade students, so there are 700  320 = 380 students in 5th grade. There are 210 girls in 5th grade so there are 380  210 = 170 boys in 5th grade. 50% of the 5th graders take MC, or 50% * 380 = 190 students in 5th grade take MC. 40% of the 4th graders take MC, or 40% * 320 = 128 students in 4th grade take MC. 90 boys in 5th grade don't take MC => the remaining 170  90 = 80 boys in 5th grade take MC. Hence there are 190  80 = 110 girls in 5th grade take MC. The number of 4th grade girls taking MC is less than 1/2 of the number of 5th grade girls taking MC. There are 110 girls in 5th grade take MC, so the number of 4th grade girls taking MC is less than 1/2 * 110 = 55 Note that there are 128 students in 4th grade taking MC, so the number of boys in 4th grade taking MC must greater than 128  55 = 73. Now, A, B, C are out. Note that there are 128 students in 4th grade taking MC, so the number of boys in 4th grade taking MC cannot greater than 128, so E is out. The answer is D.
_________________
Actual LSAT CR bank by Broall
How to solve quadratic equations  Factor quadratic equations Factor table with sign: The useful tool to solve polynomial inequalities Applying AMGM inequality into finding extreme/absolute value
New Error Log with Timer



Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4664

Re: At Mnemosyne Middle School, there are 700 students: all the students a
[#permalink]
Show Tags
27 Apr 2017, 12:02
rohit8865 wrote: mikemcgarryPlease make above question correct as said earlier thanks Dear rohit8865Done. Mike
_________________
Mike McGarry Magoosh Test Prep
Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)



Intern
Status: I am not giving up. Not yet.
Joined: 23 Jul 2015
Posts: 46

Re: At Mnemosyne Middle School, there are 700 students: all the students a
[#permalink]
Show Tags
03 May 2017, 01:56
mikemcgarry wrote: At Mnemosyne Middle School, there are 700 students: all the students are boys or girls in the 4th or 5th grade. There are 320 students in the 4th grade, and there are 210 girls in the 5th grade. Fifty percent of the 5th graders and 40% of the 4th graders take Mandarin Chinese. Ninety 5th grade boys do not take Mandarin Chinese. The number of 4th grade girls taking Mandarin Chinese is less than half of the number of 4th 5th grade girls taking Mandarin Chinese. Which of the following could be the number of 4th grade boys in Mandarin Chinese?
(A) 10 (B) 40 (C) 70 (D) 100 (E) 130This is one of a set of fifteen challenging GMAT Quant problems. To see the whole collection, as well as the OE for this question, go to: Challenging GMAT Math Practice QuestionsMike Wonderful question ruined by typos.
_________________
Cheers PeeKay



Current Student
Joined: 09 Mar 2017
Posts: 89
Location: Netherlands
Concentration: General Management, Finance

Re: At Mnemosyne Middle School, there are 700 students: all the students a
[#permalink]
Show Tags
03 May 2017, 02:35
No of students in 4th grade=320 No of students in 5th grade=380 (boys=170, girls=210) Students taking Mandarin Chinese: 4th grade: 0.4*128=128 (boys=x, girls= less than 55 (half of girls in 5th grade) 5th grade: 0.5*380=190 (boys=80, girls=110) A, B, C are crossed out because their sum will not reach 128 E is crossed out because it will exceed 130 D IMO Sent from my SMG935F using GMAT Club Forum mobile app



Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4664

Re: At Mnemosyne Middle School, there are 700 students: all the students a
[#permalink]
Show Tags
03 May 2017, 13:15
PKay wrote: mikemcgarry wrote: At Mnemosyne Middle School, there are 700 students: all the students are boys or girls in the 4th or 5th grade. There are 320 students in the 4th grade, and there are 210 girls in the 5th grade. Fifty percent of the 5th graders and 40% of the 4th graders take Mandarin Chinese. Ninety 5th grade boys do not take Mandarin Chinese. The number of 4th grade girls taking Mandarin Chinese is less than half of the number of 4th 5th grade girls taking Mandarin Chinese. Which of the following could be the number of 4th grade boys in Mandarin Chinese?
(A) 10 (B) 40 (C) 70 (D) 100 (E) 130This is one of a set of fifteen challenging GMAT Quant problems. To see the whole collection, as well as the OE for this question, go to: Challenging GMAT Math Practice QuestionsMike Wonderful question ruined by typos. Dear PKay, I corrected this in the entry at the top. Thanks for pointing this out. Mike
_________________
Mike McGarry Magoosh Test Prep
Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)



Manager
Joined: 14 May 2015
Posts: 52

At Mnemosyne Middle School, there are 700 students: all the students a
[#permalink]
Show Tags
03 May 2017, 17:10
total student=700 4th student=320 5th student=380 [G=210 B=170]
Chinese: 5th student(B+G)=190 4th student(B+G)=128
5th student: B not chn=90 B chn=17090=80 G chn=19080=110
4th G chn<(5th G chn)/2 4th G chn<110/2 4th G chn<55
if 4th G chn=54 then, 4th B chn=12854=74
if 4th G chn=0 then, 4th B chn=1280=128
74<= 4th B chn <=128
Only possible answer is D (100)



Manager
Joined: 19 Aug 2015
Posts: 106
Location: India

Re: At Mnemosyne Middle School, there are 700 students: all the students a
[#permalink]
Show Tags
05 May 2017, 08:18
Given: Total 700 4th grade 320 5th grade girls 210 50% 5th grade and 40th % 4th grade takes MC 90 5th grade boys do not take MC 4th grade girls taking MC < half of 5th grade girls taking MC Find 4th grade boys taking MC? Analysis: 4th grade has 320 so 5th grade has 700320=380 5th grade has 210 girls so number of boys = 380210=170 Out of these 170 boys, 90 do not take MC so 80 take MC Girls in 5th grade taking MC = (50% of 380)  80=110 4th grade MC = 40% of320=128 Maximum girls taking MC in 4th grade should be atleast one less than half of 5th grade girls taking MC = 110/21=54 So number of 4th grade boys taking MC is atleast 12854=74. Answer D matches(100>74) as it can not be E(130>128)



NonHuman User
Joined: 09 Sep 2013
Posts: 8111

Re: At Mnemosyne Middle School, there are 700 students: all the students a
[#permalink]
Show Tags
13 Jun 2018, 23:20
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.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources




Re: At Mnemosyne Middle School, there are 700 students: all the students a &nbs
[#permalink]
13 Jun 2018, 23:20






