$($S$12\mathrm{.}3)$ The second column in Table $12\mathrm{.}2$ shows the monthly return on the British FTSE $100$ index from January $2015$ through July $2017.$ The remaining columns show returns on the stocks of two firms$-$Executive Cheese and Paddington Beer. Both firms announced their earningsin July $2017.$ Calculate the average abnormal return of the two stocks during the month of the earnings announcement. The earnings of one of these stocks slightly