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1.7 D: Sequences and series

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Question 91

The second term of a geometric series is 3.75 and the sum to infinity is 20.

a.

Find the two possible values of rrr.

[4]
b.

Find the corresponding two possible values of 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>19S_n > 19Sn​>19.

[4]

1.7 D: Sequences and series Questions

  1. A Level
  2. /Maths
  3. /1.7 D: Sequences and series

Practise AQA A Level Maths 1.7 D: Sequences and series with exam-style questions for A Level Maths. 267 questions covering 1.7.1 Binomial expansion, 1.7.2 Types of sequence (A-level only), 1.7.3 Sigma notation (A-level only), 1.7.4 Arithmetic sequences and series (A-level only), 1.7.5 Geometric sequences and series (A-level only), and 1.7.6 Sequences and series in modelling (A-level only), matched to the AQA A Level Maths (7357) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.

Question bank