Given Information: 
Annual interest rate = r = 10% 
Accumulated amount = A = $6380.00 
Semi-annual compounding = n = 2 
Number of years = t = 38/12 = 19/6 
Required Information 
Principle amount= P = ? 
Answer: 
Principle amount= P = $4,684.05 
Step-by-step explanation: 
The principal amounts in terms of compound interest is given by 

Where 
i = r/n 
i = 0.10/2 
i = 0.05 
N = n*t 
N = 2*19/6 
N = 19/3 
So, the principal amount is 

Therefore, you need to invest $4,684.05 at 10% compounded semiannually for 38 months to get $6380.00 in savings.