15. I = Prt
... 1527.78 = 25,000·0.11·(d/360) . . . where d is the number of days.
Divide by the coefficient of d
... 1527.78·360/(25000·0.11) = d = 200
The loan is for 200 days.
17. In millions, the company borrowed 170 and received proceeds of 157.25. Thus the discount amount was 170 -157.25 = 12.75
Then the rate can be found from
... I = Prt
... 12.75 = 170·r·(270/360)
Dividing by the coefficient of r, we get ...
... r = 12.75·360/(170·270) = 0.10 = 10%
The discount rate is 10%.