Answer:
The interest paid on loan was at floating rate which means that the investor earning was lower because of lower interest rate than the interest rate he was expecting.
Explanation:
Because the bond was dependent on the floating rate in the market. The borrower kept paying the investor at the floating rate not at the fixed rate which would had increased its investment worth to $1800. As $1600 is less than $1800 so the interest rate agreed was floating rate interest.