Solution: Mark's initial amount

Mark invest's his inheritance amount in savings account with an annual interest of 3.1%. Therefore, the Mark's interest amount after 1 year is:



Therefore, total amount Mark will have after 1 year
=$30930
Now Charles also has $30000 from his inheritance.
Charles invests his inheritance in a CD paying 5.8% annual.
Therefore, interest amount for Charles after 1 year is:



Therefore, total amount Charles will have after 1 year
=$31740
Therefore, Charles will have $31740 - $30930 = $810 more than Mark