Robinson invests $12,500 in a 120-day short-term guaranteed investment certificate at a bank, based on exact simple interest at annual rate of 9%. After 60 days, the interest rate has risen to 11% and Robinson would like to redeem the certificate early and reinvest in a 60-day certificate at the higher interest rate. In order for Robinson to have no advantage in redeeming early and reinvesting at the higher rate, what early redemption penalty (deducted from the accumulated value of the investment certificate to that point) should the bank charge Robinson at the time of early redemption