homework help!

everytime i try and calculate the standard deviation of common stock A i get 0. could u help me figure out what it is?

could u also help find the standard deviation of stock B?

(Expected rate of return and risk) Syntex, Inc. is considering an investment in one of two common stocks. Given the information that follows, which investment is better, based on the risk (as measured by the standard deviation) and return? a. Given the information in the table, the expected rate of return for stock A is (Round to two decimal places.) The standard deviation of stock A is \%. (Round to two decimal places.)