An annual instalment of ₹3,500 will discharge a debt of ₹16,310 due in 4 years at y% simple interest per annum. What is the value of y? [Note: Instalments will be paid at the end of Year 1, Year 2, Year 3 and Year 4.]

Let the annual installment be x=3500.
The installments are paid at the end of Year 1, Year 2, Year 3, and Year 4.

The 1st installment (paid at the end of Year 1) will accumulate interest for 3 years.

The 2nd installment (paid at the end of Year 2) will accumulate interest for 2 years.

The 3rd installment (paid at the end of Year 3) will accumulate interest for 1 year.

The 4th installment (paid at the end of Year 4) will accumulate 0 years of interest.

The sum of the present values of these payments with accumulated interest equals the total debt A=16310:

A=4x+
100
x×y×(3+2+1+0)
​

16310=4(3500)+
100
3500×y×6
​

16310=14000+35×6×y
16310−14000=210y
2310=210y
y=
210
2310
​
=11