A survey was conducted in a super store to study the monthly turnover in the number of clients This survey revealed that:
• During the first month 5000 clients made their purchases from the store
• Each month 30% of the clients of the preceding month stopped to make their purchases from their
store and 1800 new clients joined the remaining clients of this store.
Denote Un the number of clients that make their purchases during the nth month
Let Un+1 = 0.7Un + 1800
1) Find U1 , U2 and U3
2) Show that the sequence Un is neither arithmetic nor geometric
3) Let the sequence (Vn) be denoted by Vn= 6000 – Un. Prove that Vn is a geometric sequence, whose
common ratio and 1st term are to be determined.
4) Calculate S = V1 + V2 + ….. + V6
5) Calculate Vn in terms of n
6) Deduce Un in terms of n