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or382 PART V: Analyzing and Reporting ResearchAnswer to Stretching ExerciseStatements 1 and 5 are True; 2, 3, and 4 are False.Answer to Challenge Question 1A Begin by calculating s pooledfor the four groups, being sure to note that the problem provides thestandard deviation for each group and the formula for s pooledmakes use of the variances. Thus,each standard deviation must be squared before multiplying by n 1. The value of s pooledis 6.04.__The estimated standard error of the mean ( s __ X ) is, therefore, 6.04/ n ,, 1.51. The critical valueof t at the .05 level is 2.00 (60 df ) from Table A.2. The confidence intervals for the means areA 16.4 (2.00)(1.51) 13.38 to 19.42B 29.9 (2.00)(1.51) 26.88 to 32.92C 24.6 (2.00)(1.51) 21.58 to 27.62D 19.5 (2.00)(1.51) 16.48 to 22.52B (Hint: It may be helpful to draw a figure with columns representing the mean performance ineach group and bars around the means corresponding to the confidence intervals. You may alsowant to review the information found in Box 11.5.) It can be seen that the A interval overlapsonly the D interval. The C and D intervals overlap. Although the observed pattern of groupmeans is our best estimate of the locations of the population values, the confidence intervalsalso provide information about the precision of our estimates. On the basis of these data, wemay conclude that the population mean estimated by sample mean A differs from the populationmeans represented by B and C. We will want to withhold judgment about the differencebetween A and D. We may also conclude that population means B and D differ, but admit weare uncertain about the true difference between B and C.