How do I find the cumulative average residual?

Ross Company; Westerfield, Incorporated; and Jordan Company announced a new agreement to market their respective products in China on July 18 , February 12 , and October 7 , respectively. Given the information below, calculate the cumulative abnormal return (CAR) for these stocks as a group. Assume all companies have an expected return equal to the market return. Note: A negative value should be indicated by a minus sign. Leave no cells blank - be certain to enter " 0 " wherever required. Do not round intermediate calculations. Round your answers to 1 decimal place. Ross Company; Westerfield, Incorporated; and Jordan Company announced a new agreement to market their respective products in China on July 18 , February 12 , and October 7 , respectively. Given the information below, calculate the cumulative abnormal return (CAR) for these stocks as a group. Assume all companies have an expected return equal to the market return. Note: A negative value should be indicated by a minus sign. Leave no cells blank - be certain to enter " 0 " wherever required. Do not round intermediate calculations. Round your answers to 1 decimal place