what is the risk as measured by the standard deviation of monthly return for gold during the sample period?

in Comption Sep 13 Use the mowily data (September 2013 November 2014) provided on the closing prices for Gold (GLD). NASDAQ Oil (USO) and Facebook FBX Date GLD NASDAQ USO FB 128 3771 37 50 Oct-13 128 3920 35 SO Nov 13 121 4060 33 47 Dec 13 116 4177 35 SS 120 4104 35 63 Feb-14 129 4308 37 68 Mar. 14 124 4199 39 60 124 4113 36 60 120 42:43 38 Jun-14 128 408 39 14 4370 73 124 4550 w 73 Sop14 10 4493 24 39 D-4 113 46:11 31 75 NA 47 90 74 What med by the standard devii moothilyreio during the period TE a o B 12 al 6 7 8 9 0 o W E R T Y U- O A S D F G H J Ka L C N V B N