Wang Qi deposited a sum of money in the bank last year. At that time, the annual interest rate of lump sum deposit and withdrawal was 3.25%. He calculated the principal and interest received at maturity. Solution: p- principal, also known as initial amount or present value;

I- interest rate refers to the ratio of interest to principal;

I- interest;

F- the sum of principal and interest, also known as the sum or final value of principal and interest;

N-the number of interest periods.

Interest = principal * interest rate * number of interest-bearing periods

I = P * i * n

F = P + P * i * n = P *( 1 + i * n)

Final value of simple interest (sum of principal and interest) = principal+interest = principal *( 1+ interest rate * number of interest periods)

Suppose his principal deposit is X yuan.

x + x * 3.25% * 1 = 30975

x + 0.0325x = 30975

1.0325x = 30975

∴ x = 30000

A: His deposit principal is 30,000 yuan.