Your grandfather, who is a non-taxpayer, has left savings of 5,200 for two years in an account paying an interest rate of 0.1%. [He has not noticed that the rate of interest on the account has fallen from its original level of 3.5%.] For the same period, his bank had an alternative account available at 3%. The balance in his account at the end of the two years is 5,210.40, so he earned 10.40 of interest during the two years. Calculate the cost to your grandfather of leaving the savings in the poorly paying account for two years (ie, the extra interest he could have earned if he had changed to the higher interest account).