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1.6.15 Standard formulae for geometric series (A-level only)

1.6.15 Standard formulae for geometric series (A-level only)

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Question 6

In a geometric progression, the second term is 4 and the sum of all terms is 25.

a.

Find the two possible values of the common ratio rrr.

[3]
b.

Find the corresponding two possible values of the first term aaa.

[2]
c.

Given that r r\,r takes the larger of the two possible values, find the smallest value of n n\,n for which Sn>24.5S_n > 24.5Sn​>24.5.

[3]
Markscheme

1.6.15 Standard formulae for geometric series (A-level only) Questions

  1. A Level
  2. /Maths
  3. /1.6.15 Standard formulae for geometric series (A-level only)

22 exam-style questions on OCR (MEI) A Level Maths 1.6.15 Standard formulae for geometric series (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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