8. The following table reflects abnormal returns for each of 10 stocks over a seven-day period about day zero, which is the standardized date of the sudden death of the CEO for each of the 10 firms. An analyst wants to determine whether the death announcement date represents a significant event and make appropriate portfolio adjustments when CEOs suddenly die in the future.

Day Stock 1 Stock 2 Stock 3 Stock 4 Stock 5 Stock 6 Stock 7 Stock 8 Stock 9 Stock 10 23 0.003279 20.00814 0.008945 20.00255 0.011395 20.00797 0.011223 0.014037 0.020344 0.015708 22 0.004440 20.01997 0.017064 0.003790 0.048419 0.017966 20.01098 20.02468 0.023697 0.031806 21 0.031991 0.022567 20.01350 0.026311 0.069986 0.047213 0.012632 0.038042 0.015502 0.002453 0 0.091624 0.086352 0.088165 0.077971 0.128351 0.112391 0.069263 0.089396 0.107763 0.102206 1 0.043105 0.028967 0.027764 0.006769 20.04901 20.01061 0.010702 20.00974 0.005449 0.009521 2 0.006715 0.011545 0.014355 0.013281 20.02619 20.03346 0.026330 0.003409 0.015373 0.006225 3 20.01942 20.00453 20.00708 20.00114 20.00493 0.02925 20.00783 20.03250 0.024930 0.030536

a. What are the average residuals, their standard deviations, and normal deviates for each of the seven dates?

b. What are the cumulative average residuals, their standard deviations, and normal deviates for each of the seven dates?

c. On which days are average residuals statistically significant at the 1% level? On which days are cumulative average residuals statistically significant at the 1% level?