The coupon rate given to us is 8.625%.
To find the effective annual interest rate, we will have to use the following formula:

Where ER is the Effective Rate
r is the coupon rate in per unit
n is the number of months in a year.
Thus, if we apply the formula, we will get the effective rate to be:

In percentage, the effective rate is ER=8.974% and to the nearest tenth it is 9.0%.