After 6 years, an investment is worth $8479. if the money was invested at 9% interest compounded semiannually what was the initial investment

The solution would be like this for this specific problem:

8479 = P * (1 + 0.09/2)^(2 * 6) 
8479 = P * (1 + 0.045)^12 
8479 / (1.045)^12 = P 
P = 4999.7599101968641899706115543368

If the money was invested at 9% interest compounded semiannually, the initial investment is $5000. I am hoping that this answer has satisfied your query and it will be able to help you in your endeavor, and if you would like, feel free to ask another question.

The surface area for this case is given by:
 A = 2 * pi * r ^ 2 + 2 * pi * r * h
 Where,
 r: radius of the coins
 h: height of the coin stack.
 Substituting values we have:
 A = 2 * 3.14 * (1/2) ^ 2 + 2 * 3.14 * (1/2) * (100 * (1/8))
 A = 40.82 in ^ 2
 Note: the correct thickness of the coins should be 1/8 in.
 
 Jose will need 40.82 in ^ 2 to cover the stack of coins