How did the interest cost computed in this problem? Pls help

You need to borrow $10 million for 90 days. You have the following alternatives: Issue high-grade commercial paper, with a backup line of credit costing .3% a year. a. b. Borrow from First Cookham Bank at an interest rate of .25% over LIBOR. C. Borrow from the Test Bank at prime. Given the rates currently prevailing in the market (see, for example, The Wall Street Journal), which alternative would you choose? The interest cost for the various alternatives will be computed as below: Principal Interest Rate of Type of loan (in Period cost interest Million) (Million) Issuance of High-grade 90 $10 0.61% $0.02 commercial days paper Borrow from First 90 $10 1.91% $0.05 Cookham days Bank Borrow from 90 $10 3.25% $0.08 Test Bank days From the above computation, the alternative which allows the lowest interest cost will be selected. Therefore, Issuance of High-grade Commercial Paper will be chosen having the lowest interest cost of $0.02 million