Answer:
5.657%
Explanation:
Given data:
Face value = $1,000
Current price = $640
Maturity period, t = 8 years
Now,
the compounding formula is expressed as:
Face value = Present value × 
where,
r denotes the rate, which is the pretax debt rate
n signifies the frequency of interest compounding, which for semiannual compounding is n = 2
hence, when plugging in the values, we obtain
$ 1,000= $ 640 × 
or
1.5625 = 
or
= 1.0282
or
r = 0.05657
therefore, the pretax cost of debt is calculated as 0.05657 × 100% = 5.657%