Answer:
geometric annual return = 5.23%
Step-by-step explanation:
first we must determine the return for year 4 (I will call it X)
5.1% + 31.6% - 21.2% + X = 6.75% x 4
14.5 + X = 27
X = 12.5%
geometric annual return = ⁴√(1.051 · 1.316 · 1.125 · 0.788) - 1 = ⁴√1.226132334 - 1 = 1.055287 - 1 = 0.055287 = 5.23%