Geometric series

 A sequence of numbers {Nn} is called a geometric series if Nn+1 = Nn ∙ d or Nn = N0 ∙ dn. The q is called a geometric ratio. A bank deposit is an example of a geometric series. A bank rate r gives a geometric ratio d = r+1. A deposit at a n-th month is Nn = Nn-1 ∙ d or Nn = N0 ∙ dn. A sum of n first members of the sequence Sn = N0 ∙ (dn-1)/(d-1) if d is not equal to 1 and Sn = N0nd if d=1. This model demonstrates a solution for 2 types of problems. In the first, a bank rate, start deposit and a time period are given and a deposit at given period is calculated. Otherwise a start deposit is calculated depend on deposit at given period and bank rate. You can also solve suggested problems and check you answers. Choose the Solve the problem radio button and a type of problem, insert the answer into the Answer spinbox and click the check button. If you want to see a solution of the problem click the solution button. You cannot change the problem specification in solving mode, but only in demonstration mode. To work with a different problem click the next button.