A research organization wishes to determine whether four brands of batteries for transistor radios perform equally well. Three batteries of each type were randomly selected and installed in three test radios. The number of hours of use for each battery is given below. Battery Brand Test Radio 1 2 3 4 A 25 27 20 28 B 29 38 24 37 C 21 28 16 19

a. Use the analysis of variance procedure for completely randomized designs to determine whether there is a significant difference in the mean useful life of the four types of batteries. (Ignore the fact that there are different test radios.) Use a .05 level of significance and be sure to construct the ANOVA table.

b. Now consider the three different test radios and carry out the analysis of variance procedure for a randomized block design at the .05 level of significance. Include the ANOVA table.

c. Compare the results in Parts a and b.