Below is the monthly share price data for Westpac Banking Corporation (ASX code WBC.AX) for 2021 (Source: https://finance.yahoo.com)

Month	Open $	Close $
Jan	19.37	21.13
Feb	20.80	23.82
Mar	23.87	24.41
Apr	24.42	24.98
May	25.71	26.42
June	26.29	25.81
July	25.94	24.52
Aug	24.65	25.82
Sep	25.63	26
Oct	25.61	25.67
Nov	24.50	20.52
Dec	20.50	21.35

Westpac paid a dividend of $0.58 per share on 13 May 2021 and a dividend of $0.60 per share on 5 November 2021 a. Calculate the monthly percentage returns for WBC for 2021. (Show all calculations, show answers as percentage correct to four decimal places.) b. Calculate the risk measured by the standard deviation for WBC. (Show all calculations, show answer as a percentage correct to four decimal places.)