Assume the $12,000 Treasury bill, 7% for 15 weeks. Calculate the effective rate of interest. (Use calendar year. Round your answer to the nearest hundredth percent.)

A useful formula for finding the effective interest rate on discounted notes is

... (effective rate) = r / (1 - rt)

The time period appears to be

... t = (15 weeks) * (7 days/week) * (1 year) / (365 days) = 21/73 year ≈ 0.28767 year

Then the effective rate is

... (effective rate) = 7% / (1 - 0.07*0.28767) ≈ 7.14%