Hi there

Can you please assist with helping me to calculate standard deviation for the below question? I've started to calculate the answer but I keep getting a "math error" on my calculator. Please see my answer below the question. Not sure if I should be using the percentages or if the percentages should be converted into numbers.

Question 5 Consider an investment with the following probability distribution: Return (%) Probability (%) -10 20 20 10 20 15 30 25 10 Required: 5.1. Calculate the expected return and standard deviation for this investment