Question

In a certain bank, the rate of simple interest in percent per annum during first `2` years is `3%`, `6%` during the next `3` years and `9%` during the rest of the years. If a person deposits some money to that bank, he gets an interest of `Rs2760` after `10` years. Find the principal of the person.

Answer 1

Let the person deposited `Rs x` in the bank.
During first `2` years, he gets simple interest `=Rs(x xx3xx2)/(100)=Rs(3x)/(50)`
During the next `3` years , he gets simple interest `=Rs(x xx6xx3)/(100)=Rs(9x)/(50)`
During the last `(10-2-3)` years `=5` years he gets simple interest `=Rs(x xx9xx5)/(100)=Rs(9x)/(20)`
As per question, `(3x)/(50)+(9x)/(50)+(9x)/(20)=2760`
or, `(6x+18x+45x)/(100)=2760`
or, `69x=2760xx100`, or, `x=(2760xx100)/(69)=4000`
`:.` The required prinicpal `=Rs4000`.