7The article Some Field Experience in the Use of an Accelera

7·The article -Some Field Experience in the Use of an Accelerated Method in Estimating 28-Day Strength of Concrete\" Jof Amer Concrete Institute, 1969: 895) consid-

Solution

A)

If x = 2500,

y^ = 1800 + 1.3*2500 = 5050 [ANSWER]

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b)

Using the slope, for an increase in 1 psi in x, there is a change of

delta y^ = B1 * delta x = 1.3*1

delta y^ = 1.3 (increase) [ANSWER]

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c)

Using the slope, for an increase in 100 psi in x, there is a change of

delta y^ = B1 * delta x = 1.3*100

delta y^ = 130 (increase) [ANSWER]

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d)

Using the slope, for a decrease in 100 psi in x, there is a change of

delta y^ = B1 * delta x = 1.3*(-100)

delta y^ = -130 (decrease) [ANSWER]