A depositor puts $10000 into a bank account that pays an annual effective interest rate of 4% for 10 years. If a withdrawal is made during the first 521 years, a penalty of 5% of the withdrawal amount is made. The depositor 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 $10000. Find K to the nearest dollar. a) 638 b) 980 c) 1286 d) 2140 e) None