In the Construction Industry,compressive Strength of Concrete Is a Crucial

question 58

Multiple Choice

In the construction industry,compressive strength of concrete is a crucial characteristic.Suppose for a particular residential construction job the concrete tested after 3 days should have a mean compression strength of  = 3000 psi with a standard deviation of  = 50 psi.It is known that compressive strength of concrete is Normally distributed.On a construction site,a sample of n = 5 specimens is selected and tested after 3 days.If the concrete has the desired characteristics,what is the probability that the sample mean will be larger than 3060 psi?

• A)0.996
• B)0.004
• C)0.885
• D)0.115
• E)This can't be determined because the sample size n = 5 is much too small to rely on the Normal distribution for calculation of the required probability.

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