The article "Mix Design for Optimal Strength Development of Fly Ash Concrete" (Cement and Concrete Research, 1989, Vol. 19, No. 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 twenty-eighth day are as follows (in megapascals): 40.2 30.4 28.9 30.5 22.4 25.8 18.4 14.2 15.3 Find a 95% prediction interval on the next sample that will be tested. Assume population is approximately normally distributed.
The article "Mix Design for Optimal Strength Development of Fly Ash Concrete" (Cement and Concrete Research, 1989, Vol. 19, No. 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 twenty-eighth day are as follows (in megapascals): 40.2 30.4 28.9 30.5 22.4 25.8 18.4 14.2 15.3 Find a 95% prediction interval on the next sample that will be tested. Assume population is approximately normally distributed.
Transcribed Image Text:The article “Mix Design for Optimal Strength Development of Fly Ash Concrete” (*Cement and Concrete Research*, 1989, Vol. 19, No. 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 twenty-eighth day are as follows (in megapascals):
\[
40.2, \quad 30.4, \quad 28.9, \quad 30.5, \quad 22.4, \quad 25.8, \quad 18.4, \quad 14.2, \quad 15.3
\]
Find a 95% prediction interval on the next sample that will be tested. Assume population is approximately normally distributed.
Round your answers to 2 decimal places.
\[
\Box \quad \leq \quad x_{n+1} \quad \leq \quad \Box
\]
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![The article “Mix Design for Optimal Strength Development of Fly Ash Concrete” (*Cement and Concrete Research*, 1989, Vol. 19, No. 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 twenty-eighth day are as follows (in megapascals):
\[
40.2, \quad 30.4, \quad 28.9, \quad 30.5, \quad 22.4, \quad 25.8, \quad 18.4, \quad 14.2, \quad 15.3
\]
Find a 95% prediction interval on the next sample that will be tested. Assume population is approximately normally distributed.
Round your answers to 2 decimal places.
\[
\Box \quad \leq \quad x_{n+1} \quad \leq \quad \Box
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