Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 43381

On a particular exam, the boys in a history class averaged 86 points a [#permalink]
Show Tags
30 Jun 2015, 04:05
Question Stats:
72% (00:58) correct 28% (01:11) wrong based on 189 sessions
HideShow timer Statistics



Manager
Joined: 26 Dec 2011
Posts: 120

Re: On a particular exam, the boys in a history class averaged 86 points a [#permalink]
Show Tags
30 Jun 2015, 05:07
1
This post received KUDOS
4
This post was BOOKMARKED
On a particular exam, the boys in a history class averaged 86 points and the girls in the class averaged 80 points. If the overall class average was 82 points, what was the ratio of boys to girls in the class? A. 1:4 B. 1:3 C. 1:2 D. 2:1 E. 3:1 Solution  Given that Boys average is 86 and Girls average is 80 points. Total average is 82 points. (86B+80G)/(B+G) = 82 > 4B=2G > B/G = 1/2. ANS C.
_________________
Thanks, Kudos Please



Retired Moderator
Status: On a mountain of skulls, in the castle of pain, I sit on a throne of blood.
Joined: 30 Jul 2013
Posts: 359

Re: On a particular exam, the boys in a history class averaged 86 points a [#permalink]
Show Tags
30 Jun 2015, 06:13
1
This post received KUDOS
Bunuel wrote: On a particular exam, the boys in a history class averaged 86 points and the girls in the class averaged 80 points. If the overall class average was 82 points, what was the ratio of boys to girls in the class?
A. 1:4 B. 1:3 C. 1:2 D. 2:1 E. 3:1
Kudos for a correct solution. G B 80 86 82 4 2 2 : 1 G:B=2:1 B:G=1:2 Answer: C



Manager
Joined: 20 Jul 2011
Posts: 81

Re: On a particular exam, the boys in a history class averaged 86 points a [#permalink]
Show Tags
30 Jun 2015, 09:03
2
This post received KUDOS
Bunuel wrote: On a particular exam, the boys in a history class averaged 86 points and the girls in the class averaged 80 points. If the overall class average was 82 points, what was the ratio of boys to girls in the class?
A. 1:4 B. 1:3 C. 1:2 D. 2:1 E. 3:1
Kudos for a correct solution. Solution: We can use the X method to solve similar questions B...................G 86................80 ..........82........ 2..................4 Hence, Boys: Girls => 2: 4 => 1:2 Option C



Manager
Joined: 26 Dec 2012
Posts: 148
Location: United States
Concentration: Technology, Social Entrepreneurship
WE: Information Technology (Computer Software)

On a particular exam, the boys in a history class averaged 86 points a [#permalink]
Show Tags
30 Jun 2015, 09:30
1
This post received KUDOS
Let # boys in the class=x & # of girls in class =y so we have (sum of boys)=86X (sum of girls)=80y
total average =82=> 86x+80y=82(x+y) =? we get 4x=2y so x/y =1/2
Hence answer is C Thanks,
Last edited by lipsi18 on 30 Jun 2015, 10:20, edited 1 time in total.



Senior Manager
Joined: 28 Jun 2015
Posts: 299
Concentration: Finance
GPA: 3.5

Re: On a particular exam, the boys in a history class averaged 86 points a [#permalink]
Show Tags
30 Jun 2015, 09:37
80  82  86 8682/8280 = 4/2 = 2/1. D.
_________________
I used to think the brain was the most important organ. Then I thought, look what’s telling me that.



Manager
Joined: 17 Mar 2014
Posts: 237
Location: India
Concentration: Operations, Strategy
GPA: 3.19
WE: Information Technology (Computer Software)

Re: On a particular exam, the boys in a history class averaged 86 points a [#permalink]
Show Tags
30 Jun 2015, 10:01
1
This post received KUDOS
1
This post was BOOKMARKED
86  80 82 2 4 .... hence 2:4 = 1:2 Did cross subtraction here , 8682 = 4 , 8280 = 2 Required answer = 1:2 C
_________________
Press +1 Kudos if you find this Post helpful



Manager
Joined: 07 Apr 2015
Posts: 180

Re: On a particular exam, the boys in a history class averaged 86 points a [#permalink]
Show Tags
01 Jul 2015, 06:51
1
This post received KUDOS
I think its 2:1 as question asks for the ratio of Boys to girls.
Let x be number of boys, y number of girls.
86x + 80y / (x+y) = 82
86x + 80y = 82x + 82y 4x = 2y 2x = y 2:1



Math Expert
Joined: 02 Sep 2009
Posts: 43381

Re: On a particular exam, the boys in a history class averaged 86 points a [#permalink]
Show Tags
06 Jul 2015, 01:59



Intern
Joined: 13 May 2015
Posts: 18
Concentration: Finance, General Management
GPA: 3.39

Re: On a particular exam, the boys in a history class averaged 86 points a [#permalink]
Show Tags
06 Oct 2016, 04:40
I got that 8682 & 8280 are the two sets of numbers we are using to arrive at the answer however im getting 2:1 and not 1:2..... help!



Retired Moderator
Joined: 12 Aug 2015
Posts: 2344
GRE 1: 323 Q169 V154

Re: On a particular exam, the boys in a history class averaged 86 points a [#permalink]
Show Tags
10 Dec 2016, 09:26
Here is my solution for this one> Sum(Boys scores)=\(86*B\) Sum(Girls scores)=\(80*G\) Total > \(86*B+80*G = 82*B+82*G\) Hence \(4B=2G => \frac{B}{G}=\frac{1}{2}\)
Hence C
_________________
Give me a hell yeah ...!!!!!



Intern
Joined: 14 Feb 2017
Posts: 29
Location: Australia
Concentration: Technology, Strategy
GPA: 2.61
WE: Management Consulting (Consulting)

Re: On a particular exam, the boys in a history class averaged 86 points a [#permalink]
Show Tags
01 Aug 2017, 02:22
I can't seem to apply a consistent approach to weighted average problems.
Could someone please point me to the right direction for a good explanation of the approach?



Manager
Joined: 30 May 2012
Posts: 217
Location: United States (TX)
Concentration: Finance, Marketing
GPA: 3.3
WE: Information Technology (Consulting)

Re: On a particular exam, the boys in a history class averaged 86 points a [#permalink]
Show Tags
07 Aug 2017, 08:26
ashokk138 wrote: Bunuel wrote: On a particular exam, the boys in a history class averaged 86 points and the girls in the class averaged 80 points. If the overall class average was 82 points, what was the ratio of boys to girls in the class?
A. 1:4 B. 1:3 C. 1:2 D. 2:1 E. 3:1
Kudos for a correct solution. Solution: We can use the X method to solve similar questions B...................G 86................80 ..........82........ 2..................4 Hence, Boys: Girls => 2: 4 => 1:2 Option C I have come across this  "X  method" in several posts on this forum. Is there a theory/article describing this? Seems like a sure shot approach to weighted averages. Can someone point me to the resource, please?



Manager
Joined: 24 Jun 2017
Posts: 118

Re: On a particular exam, the boys in a history class averaged 86 points a [#permalink]
Show Tags
07 Aug 2017, 11:22
lets x be the number of boys and y number of girls (86x + 80y) / (x + y) = 82 86x + 80 y = 82x + 82y 86x  82x = 82y  80y 4x = 2y 2x = y
1:2 (boys:girls)




Re: On a particular exam, the boys in a history class averaged 86 points a
[#permalink]
07 Aug 2017, 11:22






