In: Statistics and Probability
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 σ = 70. Let μ denote the true average compressive strength.
(a) What are the appropriate null and alternative hypotheses?
H0: μ = 1300
Ha: μ > 1300H0:
μ > 1300
Ha: μ =
1300 H0: μ <
1300
Ha: μ = 1300H0:
μ = 1300
Ha: μ ≠ 1300H0:
μ = 1300
Ha: μ < 1300
(b) Let
X
denote the sample average compressive strength for n = 11 randomly selected specimens. Consider the test procedure with test statistic
X
itself (not standardized). What is the probability distribution of the test statistic when H0 is true?
The test statistic has a gamma distribution.The test statistic has an exponential distribution. The test statistic has a normal distribution.The test statistic has a binomial distribution.
If
X = 1340,
find the P-value. (Round your answer to four decimal
places.)
P-value =
Should H0 be rejected using a significance
level of 0.01?
reject H0
do not reject H0
(c) What is the probability distribution of the test statistic when
μ = 1350?
The test statistic has an exponential distribution.The test statistic has a normal distribution. The test statistic has a gamma distribution.The test statistic has a binomial distribution.
State the mean and standard deviation of the test statistic. (Round
your standard deviation to three decimal places.)
mean | KN/m2 | |
standard deviation | KN/m2 |
For a test with α = 0.01, what is the probability that the
mixture will be judged unsatisfactory when in fact μ =
1350 (a type II error)? (Round your answer to four decimal
places.)