The following are the samples of lifetimes (in hours) of AA size batteries from two different brands ...

      The following are the samples of lifetimes (in hours) of AA size   batteries from two different brands:      Brand I =   [238, 247, 249, 247, 242, 244, 247, 247, 249,           244, 239,   242, 247, 248, 254, 245, 246, 244,            243, 248,   246, 244, 241, 245, 243, 250, 249,            241, 250,   243, 246, 250, 241, 246, 240, 237,            249, 245,   242, 239]              Brand II =   [245, 243, 234, 240, 242, 237, 241, 240, 240,           239, 242,   245, 236, 244, 241, 242, 235, 241,            246, 236,   232, 233, 241, 250, 244, 247, 240,            246, 239,   242, 239, 238, 241, 238, 245, 241,            242, 239,   245, 237, 243, 239, 236, 238, 237,            239, 239,   241, 242, 239]             a. Calculate   the sample means, medians of both brands.          b. Calculate   the sample variances of both the samples.          c. Give a   two sided 97% confidence interval for μ1.For the following parts, assume that   the populations follow normal distributions.   d. Give a   two sided 90% confidence interval for σ^2_1/σ^2_2