Answer:
22.5%
Step-by-step explanation:
let the standard deviation for market portfolio = σₙ
Also let the standard deviation for fully diversified portfolio = σₓ
To calculate fully diversified portfolio
fully diversified portfolio has σₓ = βσₙ
From the given question beta (β) = 1.25
Also standard deviation for market portfolio (σₙ) = 18% = 0.18
From the equation above, σₓ = βσₙ = 1.25×0.18 = 0.225
= 22.5% (converting to percentage)