It is currently Sun Jan 21, 2018 8:56 pm

 All times are UTC

 Page 1 of 2 [ 11 posts ] Go to page 1, 2  Next
 Print view Previous topic | Next topic
Author Message
 Post subject: desperate for help maths prob -Posted: Wed Apr 28, 2010 9:35 pm

Joined: Fri Feb 12, 2010 11:20 pm
Posts: 10
In class , one third of the pupils bring a teddy bear to school. Last term, each boy took 12 books out of the library, each girl took 17 books and each teddy bear took 9 books. In total 305 books were taken out.

How many girls in class?

Top

 Post subject: Posted: Wed Apr 28, 2010 9:40 pm

Joined: Fri Sep 15, 2006 8:51 am
Posts: 8598
I didn't think teddies could read??? - sorry that time of night, brain has ceased to work

Top

 Post subject: Posted: Wed Apr 28, 2010 10:17 pm

Joined: Fri Oct 30, 2009 11:08 pm
Posts: 1234
Is this an 11 plus question or Maths challenge?

I am fairly sure the answer is 7 girls

7 girls - 119 books
11 boys - 132 books

18 children thus 6 teddies taking 54 books.

total 305.

Top

 Post subject: Posted: Wed Apr 28, 2010 10:24 pm

Joined: Fri Feb 12, 2010 11:20 pm
Posts: 10
Thanks - 11+ question

what is the method (other than trial and error) of arriving at 7 girls and 11 boys -
i understand 1/3 etc from thence

Top

 Post subject: Posted: Wed Apr 28, 2010 10:34 pm

Joined: Fri Oct 30, 2009 11:08 pm
Posts: 1234
Sorry - no idea.

I did:

Teddies = 1/3 (Girls+Boys)
305 = 12xboys + 17xGirls + 9xteddies

305 = 12B + 17G + 9x 1/3 (G+B)
305 = 15B + 20 G

then got stuck on the theory so trial and errored from there, remembering that G + B had to be a number devisable by 3.
Hopefully someone with less rusty maths than me can help.

Top

 Post subject: Posted: Wed Apr 28, 2010 10:43 pm

Joined: Thu Nov 02, 2006 3:07 pm
Posts: 1149
Location: Finchley - Barnet
13 girls=221 books

remaining 84 between boys and teddies, say 4 boys 4 teddies=4x12+4x9=84

Hence given earlier answers, more than one solutions to the problem

_________________
sj355

Top

 Post subject: Posted: Thu Apr 29, 2010 7:00 am

Joined: Fri Oct 30, 2009 11:08 pm
Posts: 1234
Sorry sj355 but I disagree. You end up with 17 children. A third must have teddies so thats 5 2/3 teddies.

Taking 2/3 of a teddy to school is cruel and if his head is missing he won't be able to read the books anyway!

Top

 Post subject: Posted: Thu Apr 29, 2010 2:09 pm

Joined: Mon Mar 15, 2010 4:52 pm
Posts: 162
Is there a piece of information missing, like the number of children in the class? I think this might be needed to solve the question.

Top

 Post subject: Posted: Thu Apr 29, 2010 2:37 pm

Joined: Sat May 16, 2009 8:27 pm
Posts: 209
This is a junior maths challenge question.
This is how they answer it:

Number of boys is b
girls = g
teddy bears = 1/3 of b+g
In total boys took out 12b books
girls took out 17g books
total yaken out by bears 9 x 1/3(b+g) = 3(b+g)

So 12b + 17g +3(b+g) = 305
15b + 20g = 305

3b + 4g = 61
There are 5 positive integer solutions of this but...

If 1/3 of b + g is a positive integer, then b = 11 and g=7

This is a diophantine equation.

Top

 Post subject: Posted: Thu Apr 29, 2010 4:58 pm

Joined: Sat Mar 06, 2010 11:39 pm
Posts: 2158
We need an 'awesome' emoticon.

I'm sure the Herts papers are much easier than that! Having said that, I left the maths to OH.

Top

 Display posts from previous: All posts1 day7 days2 weeks1 month3 months6 months1 year Sort by AuthorPost timeSubject AscendingDescending
 Page 1 of 2 [ 11 posts ] Go to page 1, 2  Next

 All times are UTC

#### Who is online

Users browsing this forum: No registered users and 1 guest

 You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot post attachments in this forum

Search for:
 Jump to:  Select a forum ------------------ FORUM RULES    Forum Rules and FAQs 11 PLUS SUBJECTS    VERBAL REASONING    MATHS    ENGLISH    NON-VERBAL REASONING    CEM 11 Plus GENERAL    GENERAL 11 PLUS TOPICS    11 PLUS APPEALS    11 PLUS TUTORS    INDEPENDENT SCHOOLS    11 PLUS CDs/SOFTWARE    11 PLUS TIPS    PRIMARY    SEN and the 11 PLUS    EVERYTHING ELSE .... 11 PLUS REGIONS    Berkshire    Bexley and Bromley    Birmingham, Walsall, Wolverhampton and Wrekin    Buckinghamshire    Devon    Dorset    Essex    Essex - Redbridge    Gloucestershire    Hertfordshire (South West)    Hertfordshire (Other and North London)    Kent    Lancashire & Cumbria    Lincolnshire    Medway    Northern Ireland    Surrey (Sutton, Kingston and Wandsworth)    Trafford    Warwickshire    Wiltshire    Wirral    Yorkshire BEYOND 11 PLUS    Beyond 11 Plus - General    GCSEs    6th Form    University