Corporate Finance class, this answer is not 9.76. This is the Sample Standard Deviation, which is different than the standard deviation

Probability 0.3 Expected Return -10% 5% 0.4 0.3 15% Assume that the above table represents IBM's probability distribution of returns, based on 100 years of data (30 years with -10%, 40 years with 5%, and 30 years with 15%). What is the sample standard deviation of IBM