Problem $14-1$ Cumulative Abnormal Returns

Delta, United, and American Airlines announced purchases of planes on July $18(7/18),$ February $12(\frac{2}{12}),$ and October $7(10/7),$ respectively.

$\backslash$table$[[$Delta$,$United,American$],[,$Market,Company,,Market,Company,,Market,Company$],[$Date$,$Return,Return,Date,Return,Return,Date,Return,Return$],[7/12,-\mathrm{.}39,-\mathrm{.}57,\frac{2}{8},-\mathrm{.}88,-1\mathrm{.}16,10/1,\mathrm{.}59,\mathrm{.}42],[\frac{7}{13},\mathrm{.}00,\mathrm{.}29,\frac{2}{9},-\mathrm{.}98,-1\mathrm{.}16,\frac{10}{2},\mathrm{.}49,\mathrm{.}77],[7/16,\mathrm{.}92,1\mathrm{.}15,\frac{2}{10},\mathrm{.}49,\mathrm{.}26,\frac{10}{3},1\mathrm{.}19,1\mathrm{.}19],[\frac{7}{17},-\mathrm{.}92,-\mathrm{.}73,2/11,\mathrm{.}69,2\mathrm{.}83,10/6,19,-2\mathrm{.}14],[7/18,-2\mathrm{.}18,1\mathrm{.}08,\frac{2}{12},-\mathrm{.}39,-\mathrm{.}22,\frac{10}{7},-2\mathrm{.}29,-\mathrm{.}43],[\frac{7}{19},-\mathrm{.}93,-\mathrm{.}57,\frac{2}{15},1\mathrm{.}19,2\mathrm{.}45,10/8,\mathrm{.}59,\mathrm{.}59],[\frac{7}{20},-\mathrm{.}98,-1\mathrm{.}17,\frac{2}{16},\mathrm{.}59,\mathrm{.}59,\frac{10}{9},-\mathrm{.}39,-\mathrm{.}20],[\frac{7}{23},\mathrm{.}79,\mathrm{.}42,\frac{2}{17},-\mathrm{.}39,-\mathrm{.}25,\frac{10}{10},\mathrm{.}39,-\mathrm{.}20],[\frac{7}{24},\mathrm{.}29,\mathrm{.}14,\frac{2}{18},\mathrm{.}39,\mathrm{.}12,\frac{10}{13},\mathrm{.}00,-\mathrm{.}19]]$

Given the above information, calculate the cumulative abnormal return $($CAR$)$ for these stocks as a group. All of the stocks have a beta of $1$ and no other announcements are made. $($A negative answer should be indicated by a minus sign. Leave no cells blank be certain to enter $"0"$ wherever required. Do not round intermediate calculations and round your answers to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$

$\backslash$table$[[\backslash$table$[[$Days from$],[$announcement$]],$Abnormal returns $(R_i-R_M),\backslash$table$[[$Average abnormal$],[$return$]],\backslash$table$[[$Cumulative$],[$abnormal return$]]],[$Delta$,$United,American,Sum$],[-4],[-3],[-2],[-1],[0],[1],[2],[3],[4,,,,,,]]$