A sum of Rs. 400 becomes Rs. 448 at simple interest in 2 years. In how many years, will the sum of Rs. 550 amounts to Rs. 682 at the same rate?

If certain sum, at simple interest turns into thrice of actual amount in 4 years. Find out time to become the amount thirteen times of initial amount? 

The difference between the simple interest between the simple interest received from two different sources on ₹ 1500 for 3 years is ₹ 13.50. The difference between their rate of interest is - 

An amount doubles itself in 5 years with simple interest. What is the rate of interest per year?

What is the ratio of the simple interest earned on a certain amount at the rate of 21% per annum for 8 years to that earned on the same sum at the same rate for 21 years?  

A sum of ₹ 1750 is divided into two parts such that the interests on the first part at 8 % simple interest per annum and that on the other part at 6 % simple interest per annum are equal. The interest on each part (in rupees) is 

The simple interest for four years is one fourth of the principal. At the same rate, which amount become Rs.450 total amount in 2 years?