Answer: USD 167.92

## Explanation **Step 1: Understand the mortgage structure** - Loan amount: USD 100,000 - APR: 5% (annual) - Term: 30 years - First 5 years: Interest-only payments - After 5 years: Self-amortizing mortgage - The 61st month is the first month after the interest-only period **Step 2: Calculate monthly interest rate** Monthly interest rate = 5% / 12 = 0.41667% **Step 3: Calculate interest-only payment** For first 5 years (60 months): Monthly payment = Principal × Monthly interest rate = USD 100,000 × 0.05/12 = USD 416.67 **Step 4: Calculate self-amortizing payment** After 5 years, the remaining term is 25 years (300 months) The outstanding principal is still USD 100,000 (no principal paid during interest-only period) Monthly payment = P × [r(1+r)^n] / [(1+r)^n - 1] Where: P = USD 100,000 r = 0.05/12 = 0.0041667 n = 25 × 12 = 300 Monthly payment = 100,000 × [0.0041667(1.0041667)^300] / [(1.0041667)^300 - 1] = USD 584.59 **Step 5: Calculate principal portion in 61st month** Total payment in 61st month: USD 584.59 Interest portion in 61st month: USD 100,000 × 0.05/12 = USD 416.67 Principal portion = Total payment - Interest portion = USD 584.59 - USD 416.67 = USD 167.92 Therefore, the portion of the monthly payment applied to the principal in the 61st month is **USD 167.92**.

Author: LeetQuiz .