Question

The compression strength of a certain concrete type is normally distributed with a mean of 40 Mpa and a standard deviation of 2 Mpa (a) what portion of the concrete exceeds 43 Mpa?. (b) If for a structure it is required that concrete has a compression strength of 38 Mpa to 42 Mpa what portion of the concrete will be discarded?

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Answer #1

Here I take value of probability from standard normal distribution table in table we get value at 1.5 in part a and value at 1.0 in part b XN NoTNally distibuted Standard deviation - --3 a the Conorete exceeds 43 using Nosmal distibution teuble we et value ortion otthe Con crete exCeeds 43 MPa iz o-os& p that Concret e has Compressien strength o 38mra toVa a X.8413 - 6826 Portion of the Concrete w111 be discarded 0.6836

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