Question

MT NOI TEACHER The accompanying table gives summary data on cube compressive strength (N/mm) for concrete specimens made with a pulverized fuel-ash mix. Age Sample Sample (days) Sample Size Mean SD 58 27.97 4.88 28 74 35.74 6.41 Calculate a 99% CI for the difference between true average 7-day strength and true average 28-day strength. (Use HOW - 3-0. Round your answers to two decimal places.) N/mu? 7 Interpret your 90% CL With 99% confidence that the true difference falls outside these values with 99% confidence that the true difference falls below the lower bound. • With 99% confidence, we can say that the true difference falls between these values With 99% confidence that the true difference falls above the upper bound You may need to use the appropriate table in the Appendix of Tables to answer this question Need Help The tour

Answer 1

Si } Solution: 4.88 D=68 X = 27.97 n = 74 X = 35.74. Sa =6.a) Here, C=99% = 0.99 .2=l-C=1-0.99 = 0.0 = t0.01,68+74-2 1 -656 Nowe, 99% confidence interval is, txia, n, t02-2 C.I. =(x,- *) I taz, n, th.2-2 Si S2² ni Da - 27.97-35.74 E 1:656 (4088) ² t 16.4122 74 = -7.77 1.5758 C.I. = (-9.357 - 6:19) 99% c. I is, (-9.35 6.1g) N/mm² Interpretation with 99% confidence, we can say that the true difference falls between these values. Istanned with Camscanner