Answer:
The payoff of your portfolio shows a risk-less with time-T and stock value equal to $10.
The risk-free interest rate must be 5.26%
Explanation:
position Sr<10 Sr>10
buy stock Sr Sr
short call 0 -(Sr - 10)
long call 10 - Sr 0
total 10 10
Therefore, The payoff of your portfolio shows a risk-less with time-T and stock value equal to $10.
risk - free interest rate = [[strike price/expected value]/net cost] - 1
= [10/9.5] - 1
= 5.26%
Therefore, The risk-free interest rate must be 5.26%