In a geometric progression, the second term is 4 and the sum of all terms is 25.
Find the two possible values of the common ratio rrr.
Find the corresponding two possible values of the first term aaa.
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.
178 exam-style questions on Edexcel A Level Maths Sequences and Series, covering 3.1 Arithmetic Sequences, 3.2 Arithmetic Series, 3.3 Geometric Sequences, 3.4 Geometric Series, 3.5 Sum to Infinity, 3.6 Sigma Notation, 3.7 Recurrence Relations, and 3.8 Modelling with Series. Each one has a worked solution and a mark scheme showing where the marks go.