The bankerâ€™s discount on Rs. 1600 at 12% per annum is the same as true discount on Rs. 1680 for the same time and at the same rate. The time is :
Pick.
A) 2 months  B) 4 months  C) 5 months  D) 7 months  E) None
Sol.   S.I. on Rs. 1600 = R.D. on Rs. 1680.   âˆ´ Rs. 1600 is the P.W. of Rs. 1680, i.e., Rs. 80 is S.I. on Rs. 1600 at 12%.   âˆ´ Time = [100 * 80 / 1600 * 12] year = 3/7 year = 5 months.   Answer 5 months
<result>C</result>
The bankerâ€™s discount on Rs. 1600 at 12% per annum is the same as true discount on Rs. 1680 for the same time and at the same rate. The time is :