It is currently Tue Jan 23, 2018 2:25 am

 All times are UTC

 Page 1 of 1 [ 5 posts ]
 Print view Previous topic | Next topic
Author Message
 Posted: Thu Aug 27, 2009 11:18 am

Joined: Mon May 18, 2009 5:34 pm
Posts: 11
I am struggling with this type of question:
I can explain P of 1 green being 7/18 etc but have become stuck

1) there are 6 red, 7 green and 5 blue beads in a bag. What is the smallest number of beads taken out before i can be sure of getting at least 2 of each colour?

Ans. 15

2) In 6 years' time Mira will be twice as old as she was 3 years ago. How old is she now?
Ans. 12
why can't I do
now x-6 = 2(x+3)

x-2x = 6+6

-x = 12

3) what is the quickest way - what are they testing in this sort of question

a number can be zapped by mulitplying its digits so 235 zapped is equal to 2x3x5 = 30.
what is the smallest number which can be zapped to give 24?

Many thanks for your help; i have tried or hours especially with probability and age question.
feeling quite out of all this

Top

 Post subject: Posted: Thu Aug 27, 2009 11:48 am

Joined: Fri Nov 17, 2006 8:54 pm
Posts: 1776
Location: caversham
Quote:
1) there are 6 red, 7 green and 5 blue beads in a bag. What is the smallest number of beads taken out before i can be sure of getting at least 2 of each colour?

Ans. 15

In a way you are looking for the worst result, so you are sure to get two off each colour. Imagine it's a game and the balls are being drawn out, worst case,

7 greens, followed by
6 reds, followed by
2 blues

Total 15

You don't always have to do a mathematically proven answer, just try to work out a solution to the problem.

steve

Top

 Post subject: Posted: Thu Aug 27, 2009 11:54 am

Joined: Fri Nov 17, 2006 8:54 pm
Posts: 1776
Location: caversham
Quote:
In 6 years' time Mira will be twice as old as she was 3 years ago. How old is she now?
Ans. 12
why can't I do
now x-6 = 2(x+3)

x-2x = 6+6

-x = 12

I would use M+6=2(M-3) expand brackets
M+6=2M-6 add six to both sides
M+12=2M take M from both sides
12=M

steve

Top

 Post subject: Posted: Thu Aug 27, 2009 12:09 pm

Joined: Mon Jun 18, 2007 2:32 pm
Posts: 7140
Location: East Kent
number 3 . I'd look at the factors of 24

then choose the 3 which would give lowest 3 digit number.

My guess is that they are testing knowledge of factors and problem solving skills. I take it that this is standard format, would be a bit of a giveaway question in multiple choice!

Top

 Post subject: Posted: Thu Aug 27, 2009 6:30 pm

Joined: Mon May 18, 2009 5:34 pm
Posts: 11
Thanks steve and yoyo123 - has helped - i am sure there will be many more unless maths improves :

Top

 Display posts from previous: All posts1 day7 days2 weeks1 month3 months6 months1 year Sort by AuthorPost timeSubject AscendingDescending
 Page 1 of 1 [ 5 posts ]

 All times are UTC

#### Who is online

Users browsing this forum: No registered users and 3 guests

 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