An experimental bioreactor produces biomass at a rate that varies each week. The mass of biomass produced during the nnn-th week follows an arithmetic sequence with first term a a\,a kg and common difference d d\,d kg. The total mass of biomass produced during the first 15 weeks of the operation is 1035 kg.
Show that 4a+28d=2764a + 28d = 2764a+28d=276
Given that the total mass of biomass produced during the first 45 weeks is 405 kg, calculate the total mass produced during the first 25 weeks.
Mn M_n\,Mn is the total mass of biomass produced during the first n n\,n weeks. Explain why the value you found in part (b) is the maximum value of MnM_nMn.
63 exam-style questions on CCEA A Level Maths 3.3.4 Sequences and series (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.