Can someone solve this question? (all the parts correctly and explain pls) The a

Question

Can someone solve this question? (all the parts correctly and explain pls)

The article "Mix Design for Optimal Strength Development of Fly Ash Concrete" (Cement and Concrete Research, 1989, vol. 19(4), pp. 634-640) investigates the compressive strength of concrete when mixed with fly ash (a mixture of silica, alumina, iron, magnesium oxide, and other ingredients). The compressive strength for nine samples in dry conditions on the 28th day are as follows (in megapascals): 40.2 30.4 28.9 30.5 22.4 25.8 18.4 14.2 15.3 Determine L and U such that P(L

Explanation / Answer

(a) we are being asked to compute lower and upper confidence interval values in between population mean will lie.

(b) For lower values

L = xbar - t0.005, 8 (ssample/ n)

U = xbar + t0.005, 8 (ssample/ n)

Where xbar = sample mean ; sample of standard deviation = ssample

dF = n-1 = 8; n = 9

(c) xbar = sample mean = 25.12;

sample of standard deviation = ssample = 8.42

dF = n-1 = 8; n = 9

t0.005, 8 = 3.355

L = xbar - t0.005, 8 (ssample/ n) = 25.12 - 3.355 * (8.42/3) = 15.7036

U = xbar + t0.005, 8 (ssample/ n) = 25.12 + 3.355 * (8.42/3) = 34.5364

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