Calculate the common ratio of the sequence;

Calculate the eleventh term of the sequence;

Calculate the sum of the first 23 terms of the sequence.

2r² = 2.205     (M1)

Note: Award (M1) for correct substitution in geometric sequence formula.

r = 1.05     (A1)     (C2)

[2 marks]

2(1.05)¹⁰     (M1)

Note: Award (M1) for the correct substitution, using their answer to part (a), in geometric sequence formula.

= 3.26     (3.25778…)     (A1)(ft)     (C2)

Note: Follow through from their part (a).

[2 marks]

\(\frac{{2({{1.05}^{23}} - 1)}}{{(1.05 - 1)}}\)     (M1)

Note: Award (M1) for their correct substitution in geometric sum formula.

= 82.9     (82.8609…)     (A1)(ft)     (C2)

Notes: Accept an answer of 3.97221...if r = −1.05 is found in part (a) and used again in part (c). Follow through from their part (a).

[2 marks]

In part (a), 1.1025 proved to be a popular, but erroneous, answer. Similarly to question 4, such candidates failed to find a square root. Whilst this accuracy mark was lost for such candidates, much good work was seen in this question reflecting how well drilled the majority of candidates were in both arithmetic and geometric sequence techniques.

In part (a), 1.1025 proved to be a popular, but erroneous, answer. Similarly to question 4, such candidates failed to find a square root. Whilst this accuracy mark was lost for such candidates, much good work was seen in this question reflecting how well drilled the majority of candidates were in both arithmetic and geometric sequence techniques.

In part (a), 1.1025 proved to be a popular, but erroneous, answer. Similarly to question 4, such candidates failed to find a square root. Whilst this accuracy mark was lost for such candidates, much good work was seen in this question reflecting how well drilled the majority of candidates were in both arithmetic and geometric sequence techniques.