Homework SourseMeasuring the amt of contaminate in a lake Take 64 samples f
Measuring the amt of contaminate in a lake. Take 64 samples from lake and find the mean is 81 and standard deviation is 10. Plausibly normal, no prior info, you perform a test of hypoth that the true mean is 85 against the hypoth that is less. What is the test statistic?
-2.2
-2.8
-3.6
-2.9
-3.2
-4.1
Measuring the amt of contaminate in a lake. Take 64 samples from lake and find the mean is 81 and standard deviation is 10. Plausibly normal, no prior info, you perform a test of hypoth that the true mean is 85 against the hypoth that is less. What is the test statistic?
-2.2
-2.8
-3.6
-2.9
-3.2
-4.1
-2.2
-2.8
-3.6
-2.9
-3.2
-4.1
Solution
Formulating the null and alternative hypotheses,
Ho: u >= 85
Ha: u < 85
As we can see, this is a left tailed test.
Thus, getting the critical z, as alpha = 0.1 ,
alpha = 0.1
zcrit = - 1.281551566
Getting the test statistic, as
X = sample mean = 81
uo = hypothesized mean = 85
n = sample size = 64
s = standard deviation = 10
Thus, z = (X - uo) * sqrt(n) / s = -3.2 [option e, answer]
