Interest Rate
A certain UK supmarket has a Xmas Saving Card. One puts money on it throughout the year and around November a bonus is added depend on how much has been saved. For example, saving the maximum of £280 earns a £15 bonus.
We can easily see this is a very good rate of interest as £15 on and investment of £280 over and entire year would be over 7.2%. However, one can save £50 per month for 5 months + £30 for one month and still earn the same bonus. If one were to do that, starting in April, is there a simple formula for calculating the effective rate of interest?
We can easily see this is a very good rate of interest as £15 on and investment of £280 over and entire year would be over 7.2%. However, one can save £50 per month for 5 months + £30 for one month and still earn the same bonus. If one were to do that, starting in April, is there a simple formula for calculating the effective rate of interest?
