If a mortgage pool consists of five 10 FRMs totaling 500000

If a mortgage pool consists of five 10% FRMs totaling $500,000, five 9% FRMs totaling $450,000 and ten 8% FRMs totaling $750,000, such that the total value of the pool is $1.7M, what is the weighted average coupon (WAC) rate (in percent)?

W*x = w1 * x1 + w2 * x2 + w3 * x3 +......+ wn * xn

avg % = (10*0.5 + 9* 0.45 + 8 * 0.75)/1.7 = 8.85%