# Maths - C1/C2 series help

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Thread starter 5 years ago
#1
Hi, can someone help me out with working out which 'n' value to use when using the formulas for both arithmetic and geometric progressions. I always seem to use the wrong one which is fine usually in C2 because they allow 2 extra n values but they dont on c1.
0
5 years ago
#2
It depends entirely on the question, give me an example...
0
5 years ago
#3
In an arithmetic or geometric progression, if they ask you to find, say, the 15th term, then n=15

If you're finding the sum of an arithmetic or geometric series, and you're asked to find the sum of the first 10 terms, then n=10

Not much else to say really? I'm guessing you don't do OCR Maths though, as you only come across progressions in C2
0
5 years ago
#4
Arithmetic
a = first term
n = position of term
d = difference

Geometric
a = first term
r = ratio
n = position of term

Depending on what they ask you use the correct formula. They always tell you whether you should be using arithmetic or geometric. You substitute all information given and will usually be left with one variable in which case you solve it. They can leave you with two variables in which you use simultaneous equations. Hope this helps!
0
5 years ago
#5
does anyone know if its possible to get the 2013 june ocr maths paper? mainly c1, c2 , s1 ?
0
5 years ago
#6
(Original post by Username13)
does anyone know if its possible to get the 2013 june ocr maths paper? mainly c1, c2 , s1 ?
I've got all the June 2013 papers via my school's online account (and mark schemes)...which would you like me to upload here?
1
5 years ago
#7
(Original post by Tappouni)
I've got all the June 2013 papers via my school's online account (and mark schemes)...which would you like me to upload here?
Core 1
Core 2
Statistics 1

If you don't mind?

THANKS !!
0
5 years ago
#8
(Original post by Username13)
Core 1
Core 2
Statistics 1

If you don't mind?

THANKS !!
No problem!! Happy to help I've included the mark schemes too
1
5 years ago
#9
(Original post by Tappouni)
No problem!! Happy to help I've included the mark schemes too
awesome thanks
0
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