http://passyworldofmathematics.com/Images/pwmImagesFour/SimpleInterestOne550x420JPG.jpg
Use the formula given here. Plug in what you know and then solve for T. Do this for all your questions, solving for whatever you don't know.
In how much time would the simple interest on a certain sum be 0.125 times the principle at 10% per annum?
2 answers
I = Po*r*t = 0.125Po.
Po*0.1*t = 0.125Po.
t = 1.25 yrs. = 15 Months.
Po*0.1*t = 0.125Po.
t = 1.25 yrs. = 15 Months.