Financial Management : Return and standard deviations

The market and Stock J have the following probability distributions:
Probability                          rM                          rJ
   0.3                                       15%                        20%
0.4                                          9                              5
0.3                                          18                           12
a. Calculate the expected rates of return for the market and Stock J.
b. Calculate the standard deviations for the market and Stock J.

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