Answer:
5.25%
Explanation:
Mathematically, investing at the 3-year risk-free zero rate should be the same as investing at a 2-year risk-free zero rate and one-year forward rate beginning in two years as shown thus
(1+S3)^3=(1+S2)^2*(1+y2y1)^1
S3=4.75%
S2=4.5%
y2y1=unknown
(1+4.75%)^3=(1+4.5%)^2*(1+y2y1)
1+y2y1=(1+4.75%)^3/(1+4.5%)^2
y2y1=((1+4.75%)^3/(1+4.5%)^2)-1
y2y1=5.25%