Without using excel.

You are provided the following probability distribution of returns: Security B -1.88% -4.28% -11.48% -13.08% Security C 1.94% 3.14% 6.74% 7.54% Security D Probability 15% 35% 20% 30% Security A 8% 5% -4% -6% 3% 3% 3% 3% a. Comput the mean and standard deviation for all our securities. b. Compute the correlation coefficient between: Security A and B, Security A and C, and Security A and D c. Which security is the risk-free security? Explain your answer using the statistical measures that have already been computed