The accompanying table gives summary data on cube compressivestrength (N/mm2) for
Chapter 9, Problem 12(choose chapter or problem)
The accompanying table gives summary data on cube compressivestrength (N/mm2) for concrete specimens madewith a pulverized fuel-ash mix (A Study of Twenty-Five-Year-Old Pulverized Fuel Ash Concrete Used in FoundationStructures, Proc. Inst. Civ. Engrs., Mar. 1985: 149165):Age Sample Sample Sample(days) Size Mean SD7 68 26.99 4.8928 74 35.76 6.43 Calculate and interpret a 99% CI for the difference betweentrue average 7-day strength and true average 28-daystrength.
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