On March 2, a Treasury bill expiring on April 20 had a bid discount of 5.86, and an ask discount of 5.80. What is the best estimate of the risk-free rate as given in the text?
a. 5.86 %
b. 5.83 %
c. 6.11 %
d. 6.14 %
e. none of the above
The answer is C but how to calculate it?