On 2001/4/1, Peter borrowed $2000, agreeing to pay interest at 3.7%/year compounded monthly. He paid $400 on 2004/5/1 and $500 on 2007/3/1. He will make two more payments on 2011/4/01 and 2015/8/01, with the payment on 2011/4/01 being 2 times that on 2015/8/01. What payment will he make on 2015/8/01? Remark: Dates are given in the format YYYY/MM/DD.