Use the data given in the text file "PLASTIC.txt" to answer the following questions. (i) Find the estimates of the mean hardness when the elapsed time is 20, 30 , and 40 bours, respectively. (ii) Calculate the confidenee intervals for the mean hardness when the clapsed time is 20,30 , and 40 hours. respectively, using Bonferroni procedure with a 95% family confidence coefficient.
a. (i) 210.32,231.54,251.63; (ii) (202.13,219.33),(226.23,228.67),(245.276,251.73)
b. (i) 208.21,225,34,247,71; (ii) (207,77,214,93),(229.73,235.67),(249.295,257.23)
c. (i) 209.29,229.63,249.98; (ii) (205.12,213.12),(226.23,232.22),(245.917,254.13)
d (i) 209,29,22963,249.98; (ii) (206.34,212.24),(22738,231.48),(246.298,253.65)

a. A
b. B
c. C
d. D