A mixture of pulverized fuel ash and Portland cement to be used for grouting should have a compressive strength of more than 1300 KN/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 is normally distributed with ? = 56. Let ? denote the true average compressive strength B)Let X denote the sample average compressive strength for n = 12 randomly selected specimens.

Consider the test procedure with test statistic X and rejection region x ? 1331.26. mean of the test statistic KN/m2