To Find Principal

We are given *n*, A, and r

We have to find P by the formula

__Example 01__**:**

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

__Solution__**:**

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

We know that

To Find Rate

When P,

*n*, A are given

We have to find r by the using same formula

__Example 02__**:**

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

__Solution__**:**

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

Using