Answer:
The effective interest rate, rounded to the nearest tenth, is 0.1%.
Step-by-step explanation:
The banker's rule is the simple interest formula.
The simple interest formula is given by:

In which E are the earnings, P is the principal(the initial amount of money), I is the interest rate(yearly) and t is the time, in years.
The effective interest rate is given by the following formula:
.
In this problem, we have that:
A man makes a simple discount note for $6,200, at an ordinary bank discount rate of 8.84%, for 40 days. We consider that the year has 360 days. This means that
.
So

The effective interest rate is

The effective interest rate, rounded to the nearest tenth, is 0.1%.