You deposit $3000 in an account that pays 7% interest compounded semiannually. After 4 years, the interest rate is increased to 7.28% compounded quarterly. What will be the value of the account after 8 years?

The multiplier for the first 4 years is

... m1 = (1 +.07/2) ^ (2*4) ≈ 1.316809

The multiplier for the last 4 years is

... m2 = (1 +.0728/4) ^ (4*4) ≈ 1.334534

So the value at the end of 8 years will be

... $3000*m1*m2 ≈ $5,271.98