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maths problems

Posted: Sun Aug 16, 2009 11:43 pm
by toy
Help please!
Q1:
Twi die are thrown together and the numbers shown are added together. This is called the score. Score=3.
What is the most likely score when 2 die are thrown?
Ans:
3
7
8
6
5

Q2
Circle the shape or shapes with 2 lines of symmetry.
square, circle, rectangle, regular pentagon, rhombus, kite
DS chose only rectangle but was marked wrong.
Thanks

Posted: Sun Aug 16, 2009 11:57 pm
by T.i.p.s.y
Q1
There are the most possible ways of scoring 7, so you are most likely to throw a score of 7.

1,6
2,5
3,4

Q2

A rhombus (often called a diamond) is a parallelogram with four equal sides so it has two lines of symmetry.

Posted: Mon Aug 17, 2009 12:09 am
by T-4-2
Tipsy, where have you been? I've been looking for you in the Indie section!

Posted: Mon Aug 17, 2009 12:18 am
by T.i.p.s.y
I'm on a sabbatical! :lol: 10 weeks summer holiday is taking its toll and I have been roped in to write the maths section of a book :o so am very busy.

Thanks for asking! :)

Posted: Mon Aug 17, 2009 1:13 am
by toy
Hi Tipsy, DS and I went on BBC and confirmed that a rhombus has no line of symmetry! clarity please.
I still don't question 1 either. DS chose 7 but it was only a guess.
Thanks

Posted: Mon Aug 17, 2009 1:54 am
by T.i.p.s.y
My forte is not explaining things well in English so here is a quote from a well known site:

Q2
Every rhombus has two diagonals connecting opposite pairs of vertices. Using congruent triangles, one can prove that the rhombus is symmetric across each of these diagonals.

from the BBC website:
A rhombus has four equal sides and also has its opposite sides parallel. It is formed by joining two identical isosceles triangles base to base.
Its diagonals are not equal but cut each other in half at right angles. Both diagonals are lines of symmetry.

Q1

If you have 2 die there are only a limited combination of rolls that will give you numbers 2 and 12 (two 1's and two 6's respectively). The number 7 uses the most combinations of dice than any other number.

This website may help you understand better - or confuse you! :lol:

http://www.knowyourluck.com/dice2t.html

Posted: Mon Aug 17, 2009 3:43 pm
by toy
Thanks Tipsy for that site. Can I please have the popular site for the rhombus too.
DS and I went on the link below, don't know how to explain to him that bbc is wrong.

http://www.bbc.co.uk/schools/ks2bitesiz ... pes6.shtml

Posted: Mon Aug 17, 2009 7:47 pm
by solimum
On the BBC site the shape at the bottom labelled a parallellogram does not have all 4 sides equal and has no lines of symmetry. A rhombus is defined here:

http://www.tiscali.co.uk/reference/ency ... 36058.html

as having all 4 sides equal therefore has axes of symmetries along the diagonals as descibed by other posters. Often these seem to be a case of difficulties in definitions, especially when one type of shape is a special case of a wider category (eg a square is a special case of a rectangle, a rhombus is a special parallelogram, all are special cases of quadrilateral). They can often be confusing and sometimes oversimplified. Not being involved in KS2 any more I'm not sure what the current "best" definitions are - do "kite" and "diamond" have tidy descriptions?