The fourth term of a geometric series is 10 and the seventh term of the series is 80.
For this series, find
the common ratio,
the first term,
the sum of the first 20 terms, giving your answer to the nearest whole number.
Practise Edexcel A Level Old Maths Sequences and Series with exam-style questions for A Level Old Maths. 10 questions, matched to the Edexcel A Level Old Maths (9371) specification and written in Unit exams C1, C2, C3 and C4 plus two applied units (e.g. S1 and M1) 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.