Number of periods to be compounded: 4 (quarters)
Interest rate per quarter is 8/4=2%. Growth after 1 year (4 quarters)=1.024=1.08243216.
Total amount to be repaid: 6000×1.024=$6,494.59
Total interest earned: $6,494.59-$6,000=$494.59
(For your information, if this had been simple interest, the interest would have been only $480.)