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PostPosted: Mon Aug 06, 2012 11:15 am 
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Joined: Sat Jul 28, 2012 10:34 am
Posts: 39
Ok so all members of family have had a go at this but just can't do it!!

2 [24] 36 3 [36] 48

5 [?] 72

Find the missing number!!!


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PostPosted: Mon Aug 06, 2012 11:17 am 
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Joined: Tue Oct 27, 2009 8:19 pm
Posts: 6257
60?

2x12=24
24+12=36
3x12=36
36+12=48

Then
5x12=60
60+12=72

Of course this may all be rubbish :lol:


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PostPosted: Mon Aug 06, 2012 4:00 pm 
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Joined: Thu Jun 14, 2012 9:28 am
Posts: 121
Not rubbish at all Doodles! Well done in fact.
Tagore


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PostPosted: Thu Aug 09, 2012 10:03 pm 
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Joined: Wed Apr 25, 2007 12:02 pm
Posts: 149
Location: Birkenhead
Strangely if you just take 12 from the number on the right you get the same
answer

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Denise J


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PostPosted: Fri Aug 10, 2012 8:47 am 
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Joined: Sun Jan 13, 2008 6:18 pm
Posts: 238
Location: Gloucestershire
Quote:
2 [24] 36 3 [36] 48

5 [?] 72

Find the missing number!!!


I believe you need to use the outside numbers to arrive at the middle number so:

(2 x 36) / (2 + 1) = 24
(3 x 48) / (3 + 1) = 36
(5 X 72) / (5 + 1) = 60


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PostPosted: Sat Sep 08, 2012 3:58 pm 
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Joined: Sat Sep 08, 2012 10:41 am
Posts: 7
I'm reading these forums with interest to see what sort of things get asked in these tests, and I've never come across these types of problems before.

If the three numbers can be termed A [B] and C

I take it that what the kid needs to do is (in a roundabout way) generate a method for caluclating B that uses A and C using +, -, / and x and any constants they require?

Thus for the question above we have

2 [24] 36
3 [36] 48 and
5 [x] 72

I presume they have to show working too?

Would it be ok to show it as:

b=((A+1)x12)-12

Sorry, I'm new to this!


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PostPosted: Sat Sep 08, 2012 4:24 pm 
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Joined: Mon Aug 22, 2011 8:20 pm
Posts: 1706
Location: Warwickshire
Len Scap wrote:
I presume they have to show working too?
No - just the answer
Quote:
Would it be ok to show it as:
b=((A+1)x12)-12
You don't need to show how you got there - but you should be looking for an answer that uses both A and C


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PostPosted: Sat Sep 08, 2012 4:25 pm 
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Joined: Wed Jul 07, 2010 11:04 am
Posts: 455
Hi, no they just have to mark the right box. Of course they have to be able to work out the answer in order to that so they do need to be familiar with the question type and able to look at numbers logically. Lots of practice ahead of time will help.

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Everyone is a genius, but if you judge a fish by its ability to climb a tree, it will think it is stupid.


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PostPosted: Sat Sep 08, 2012 4:33 pm 
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Joined: Sat Sep 08, 2012 10:41 am
Posts: 7
Okanagan wrote:
Len Scap wrote:
I presume they have to show working too?
No - just the answer
Quote:
Would it be ok to show it as:
b=((A+1)x12)-12
You don't need to show how you got there - but you should be looking for an answer that uses both A and C


Ok - thanks.

I actually ended up with two equations:

c=(a+1)x12 and
b = c-12

I just substituted to get to b=((a+1)x12)-12, but I used a and c to get there.


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