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PostPosted: Sat Aug 04, 2012 11:15 am 
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Joined: Sat Aug 04, 2012 11:07 am
Posts: 1
Could someone help with this question ? I simply don't get this one.

3 numbers related in the same way:

(14 [15] 17) (2 [5] 9)
(8 [?] 23)

Answer is 15 but I just don't understand how they work this one out.

Can someone explain this one to me please?!

Thank you!


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PostPosted: Sat Aug 04, 2012 12:19 pm 
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Joined: Sun Jul 06, 2008 2:36 pm
Posts: 107
titou18 wrote:
Could someone help with this question ? I simply don't get this one.

3 numbers related in the same way:

(14 [15] 17) (2 [5] 9)
(8 [?] 23)

Answer is 15 but I just don't understand how they work this one out.

Can someone explain this one to me please?!

Thank you!


Hi

My DD has just done this paper.

For this one, she added both outside numbers together, subtracted one and then divided by 2 to get the middle number.

PD101


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PostPosted: Sat Aug 04, 2012 12:28 pm 
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Joined: Tue Oct 04, 2011 8:44 am
Posts: 1389
Location: Reading
I have an answer but it wasn't nice to work out.

Using 14[15]17 as example

14 + 17 = 31
31*2 =62
62-2 60
60/4=15

So once you see that 8+23 also =31 then the answer must also be 15.

My DD would not get this one in a million years.


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PostPosted: Sat Aug 04, 2012 12:29 pm 
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Joined: Tue Oct 04, 2011 8:44 am
Posts: 1389
Location: Reading
pixiedust101 wrote:
titou18 wrote:
Could someone help with this question ? I simply don't get this one.

3 numbers related in the same way:

(14 [15] 17) (2 [5] 9)
(8 [?] 23)

Answer is 15 but I just don't understand how they work this one out.

Can someone explain this one to me please?!

Thank you!


Hi

My DD has just done this paper.

For this one, she added both outside numbers together, subtracted one and then divided by 2 to get the middle number.

PD101


Certainly simpler than my way :D


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PostPosted: Sat Aug 04, 2012 3:08 pm 
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Joined: Fri Jul 16, 2010 11:54 am
Posts: 78
My DS did a complicated method but he solved it really quickly,less than 10 seconds.

As per him

(14 [15] 17) (2 [5] 9)
(8 [?] 23)

2-1 =1+9=10/2=5
14-1=13+17=30/2=15
So, 8-1=7+23=30/2=15

It looks like a three step question,don't know whether his method is correct, but I could't solve it! :roll


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