Problem Solving on maths 11+ papers

[Guest55]

Algebra isn't needed - in fact it confuses.

Please don't use letters where logic works!

[fatbananas]

Kingfisher, thanks for your reply. In fact, I have a DS, who therefore won't be sitting the CoL exams , but I've been printing off as many papers as I can, to get variety. The exams DS will be sitting are an unknown quantity at the moment, as the test provider is likely to change, so I think all kinds of questions will help him not be phased by topics presented in different ways.

I've got no idea whether he would be any good at these kinds of questions, yet, but I know I'm not! I know they do have this sort of thing (though maybe not quite as long) in some grammar school exams, so they ought to be something we look at. But, as you say, perhaps not yet (he's in year 4) ...

Congratulations to your daughter!

[Kingfisher]

(From Kingfisher's daughter, age 11) Hi, my mum asked me to have a go at these - she's hopeless at maths! I sat down and worked out the second one (with her giving me useless advice )
So:

Some fairy cakes are delivered for Janey's party.
Janey can use big plates or small plates to put the cakes on.
If she uses big plates she can put 7 cakes on each plate with 5 left over.
If she uses small plates she can put 5 cakes on each plate with 3 left over.

Looking at this, you know the number of cakes is going to have to be a both a multiple of 7 add 5 and a multiple of 5 add 3.

What is the smallest number of cakes that were delivered for Janey's party?
The smallest number of cakes are delivered for Janey's party.

Trial and error gives you 33 (my mum ended up somewhere in the 70s]. Just work through the 7 times table, adding on five. Then take away 3 and see if you have a multiple of 5 left.

(a) If she only used big plates for the cakes, how many big plates would she need?
(b) If she only used small plates for the cakes, how many small plates would she need?

This bit's fairly easy. A= 5 and B= 7 Some people find that idea quite difficult, but the ALL cakes have to go on a plate, so you add an extra one. Hope you find this helpful!

[fatbananas]

Thank you, Miss Kingfisher. That's really helpful.

Guest55, how would you encourage your students to do it?

[Kingfisher]

Algebra isn't needed - in fact it confuses.

Please don't use letters where logic works!

Guest55 has mentioned that the logical approach appears to be best. It worked for me
Also, there is no 'one method fits all', you have to adapt to each question separately - this question is unlikely to come up word for word in the exam, and while a similar one may be in the paper, a different method may need to be used.
Good luck to your son, I hope he does well - I took my 11 plus last year so I know it can seem quite scary, and while it was daunting initially, I found that, by the end, I enjoyed it.

Miss Kingfisher