Refer to Exercise 1 in Section 9.1. A scientist wants to determine whether the mean strength of specimens cured at 30°C differs from the mean strengths of specimens cured at 0°C, 10°C, and 20°C.

a. Use the Bonferroni method to determine which of the means, if any, for 0°C, 10°C, and 20°C differ from the mean for 30°C. Use the 5% level.

b. Use the Tukey–Kramer method to determine which of the means, if any, 0°C, 10°C, and 20°C differ from the mean for 30°C. Use the 5% level.

c. Which is the more powerful method to find all the treatments whose means differ from that of the 30°C temperature, the Bonferroni method or the Tukey–Kramer method?