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$10,366 is the difference between the interest expense at the end of year 1 ($210,366) and the coupon payment ($200,000).
you need to adjust the balance sheet’s bond liability end of 1st period to calculate 2nd period’s interest expense.
the ending bond liability = beginning bond liability ($4,674,802) + change in bond liability ($210,366 – 200,000) = $4,685,168
therefore, 2nd period’s interest expense is 4.5% x 4,685,168 = $210,833