# More Examples of Compound Interest

To find the principal

We are given *n*, A, and r

We have to find P by the formula

__Example 01__**:**

Find the principal when the compound interest for 4 years at 6% is 525.

__Solution__**:**

Let principal = P, , r = 6%, C.I = 525

We know that

To find the rate

When P, *n*, A are given

We have to find r by using the same formula

__Example 02__**:**

Find the rate of interest compounded per annum for 3 years so that Rs.4000 becomes 4635.50

__Solution__**:**

Let A = 4635.50, P = 4000, , r = ?

Using