Can someone please help explain this and how to do it via the financial calculator and or how to solve it in excel, please and thank you

0/1 pts Question 19 You purchased stock for $25,000 ten years ago. Now the stock is worth $10,000. What was your annual rate of return? You Answered -9.1% 9.6% Correct Answer O-8.8% 0-105% no solution Question 20 0/1 pts Consider the following returns and states of the economy for TZ.Com: Economy Probability Return Weak 20% -7% Normal 20% 11% Strong 60% 23% What is the standard deviation of TZ's returns? SET YOUR CALCULATOR TO FOUR DECIMAL PLACES AND ROUND TO 2 DECIMAL PLACES AT THE END. DO NOT ENTER THE %. FOR EXAMPLE, IF YOUR ANSWER IS 7.7011% ENTER IT AS 7.70. You Answered 5.5 Correct Answer 11.76 margin of error +/-0.5