Question

The banker's discount on Rs. 1600 at 15% per annum is the same as true discount on Rs. 1680 for the same time and at the same rate. The time is:

Answer 1

Simple Interest → S.I

True Discount → TD

Present Worth → PW

S.I on ₹1600 = TD on ₹1680

₹1600 is the PW of ₹1680

That is 80 is on ₹1600 at 15%

Required time = [100×80/(1600×15)]

= 8000/1600×15

= 5/15

= 1/3 year

= 1/3 ×12 months

= 4 months

Hope it helps