Answer:
12.22% will be the forecast rate over the next 10-years framework.
Explanation:
Blume's formula is used to do an average of both, the arithmetic and geometric mean. The formula is as follow:
(T-1)/(N-1) * Geometric average + (N-T)/(N-1) * Arithmetic average
Where:
T = forecast period = 10 years for this case
N= the data we have samples = 30 years for this particular project
Then we have thegeometric and arthmetic mean
We place them on the formula and solve for Return on Equity
Return = (10-1)/(30-1) * 0.105 + (30-10)/(30-1) * 0.13
Return = (9/29)*.105 + (20/29)*.13 = 0.122241379 = 12.22%
12.22% will be the forecast rate over the next 10-years framework.