6-16. (Expect have been provided the prices fo have ben provided the rics for Citigroupdthe S ed return, standard deviation, and the capital asset pricing model) Below S&P 500 Index 500 ndex. CITIGROUP S&P 500 INDEX 2014 May June July August September October November December 2015 $47.57 47.10 48.91 51.65 51.82 53.53 53.97 54.11 $1,924 1,960 1,931 2,003 1,972 2,018 2,068 2,059 January February March April May 46.95 52.42 51.52 53.32 54.97 1,995 2,105 2,068 2,086 2,128 a. Calculate the monthly holding-period returns for Citigroup and the S&P 500 Index. b. What are the average monthly returns and standard deviations for each? c. Graph the Citigroup returns against the S&P 500 Index returns. d. Use a spreadsheet to compute the slope of the characteristic line. e. Interpret your findings