Cannot see this one.....

Advice on 11 Plus VR papers and problems

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Amanda123
Posts: 3
Joined: Mon Jul 21, 2008 3:14 pm

Cannot see this one.....

Post by Amanda123 »

Hi

I am confused with this sequence question

The answer is 17 but i cannot understand how to get to it ???

39 37 35 33 30 28 24 22 ----

Please would someone put me out of my misery

Thanks
stevew61
Posts: 1786
Joined: Fri Nov 17, 2006 9:54 pm
Location: caversham

Re: Cannot see this one.....

Post by stevew61 »

Amanda123 wrote: 39 37 35 33 30 28 24 22 ----

Please would someone put me out of my misery

Thanks
-2 -2 -2 -3 -2 -4 -2 -?

two sequences -2 alternated with

-2 -3 -4 -? so -5

22-5=17

I think its the -2 -2 -2 at the start that confuses. :)


steve
KenR
Posts: 1506
Joined: Fri Mar 17, 2006 6:12 pm
Location: Birmingham

Post by KenR »

39 37 35 33 30 28 24 22 ----
This is 2 series sets interleaved with

the odd series terms 39 35 30 24 ... being the 1st set and

the even series terms 37 33 28 22 being the 2nd set

For both series the differences between the terms are -4, -5, -6 etc

the next term in the 1st series is therefore 24 - 7 = 17

A good quick trick is to count the total number of terms in the series - if it's 6 or more it often means there are 2 series interleaved. Single series often only have 5 terms.
Amanda123
Posts: 3
Joined: Mon Jul 21, 2008 3:14 pm

Thanks for this - much apprecited

Post by Amanda123 »

[quote="KenR"][quote]39 37 35 33 30 28 24 22 ----
[/quote]

This is 2 series sets interleaved with

the odd series terms 39 35 30 24 ... being the 1st set and

the even series terms 37 33 28 22 being the 2nd set

For both series the differences between the terms are -4, -5, -6 etc

the next term in the 1st series is therefore 24 - 7 = 17

A good quick trick is to count the total number of terms in the series - if it's 6 or more it often means there are 2 series interleaved. Single series often only have 5 terms.[/quote] :D
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