Enrique has determined that investing $600 per month will enable him to accumulate $11, 150 in 11 years and that investing $900 per month will enable him to accumulate $18,950 over the same period. Estimate, using linear interpolation, how much he would have to invest each month to accumulate exactly $16,000. It would take $ a month to accumulate $16,000. (Round to the nearest cent as needed.)