𝐴(𝑟)=3200(1+𝑟)4

Question

If $3200 is invested at an interest rate, 𝑟, compounded annually, the amount in the account after 4 years is given by the polynomial function 𝐴(𝑟)=3200(1+𝑟)4. Here, r is used as a decimal, so if r= 5% then use r= 0.05. A) Describe how this A(r) function is transformed from the graph of 𝑓(𝑟)=𝑟4.Use terminology.

B) Graph this function in an appropriate window and draw your graph (use [0, 1] for x(or r) in your window). 

C) At what interest rate would the money need to be invested in order to yield $10000 after 4 years? answer graphically and algebraically. Round your answers to the nearest 0.01% (or 0.0001).

Answer 1

A: 3200 stretches the graph vertically, (1+r) shifts the graph left by 1.

C: 32.96%