Carl puts 10,000 into a bank account that pays an effective annual interest rate of 4% for ten years, with interest credited at the end of each year. If a withdrawal is made during the first five and one-half years, a penalty of 5% of the withdrawal is made. Call withdraws K at the end of each of years 4, 5, 6 and 7. The balance in the account at the end of year 10 is 10,000. Calculate K