The cost of the bond was 90/100 times $10,000, that is, $9,000 total.
The annual interest is 5% of $10,000, that is, $500.
The current yield is 5% divided by (90/100), that is 5.555%; round to 5.6% as instructed.
The yield that real bond buyers would be more interested in is the yield
to maturity, but this cannot be calculated without knowing the term
(number of years). If it's a short term bond that will pay you back
$10,000 in just a few years, that would add several percent to the yield,
but if it's a 15-year bond the growth of the $9,000 to $10,000 adds only
a fraction of 1% to the yield.
