Question

A mixture of pulverized fuel ash and Portland cement to be used for grouting should have an average compressive strength of more than 1300KN=m2. The mixture will not be used unless experimental evidence indicates conclusively that the strength specification has been met. Suppose compressive strength for specimens of this mixture has standard deviation ? = 60. Let ? denote the true average compressive strength.

Answer 1

Answer:

Check the explanation

Step-by-step explanation:

Hypotheses are:

$H_o$ : μ 1300, $H_a$ : μ > 1300

The distribution of test statistics will be normal with mean

mean 1300

and standard deviation

$sd=\frac{\sigma}{\sqrt{n}}=\frac{68}{\sqrt{11}}$=20.50277

Now z-score for  T-1331.26 and μ 1300 is

-1300-1.52 1331.26 1300 68/V11

$z=\frac{1331.26-1300}{68/\sqrt{11}}= 1.52$

So the probability distribution of the test statistic when H0 is true is

a = P(z > 1.5247) = 0.0643