Question

For each of the following exercises: For each test use either the critical value or the P-value method you are not required to use both.
a.) State the claim and the hypothesis.
b.) Find the critical value(s) and describe the critical (rejection) region You can choose to use the P-value method in this case state the P-value after the test value.
c.) Compute the test value (statistic)
d.) Make a decision
e.) Summarize the results (conclusion)

A study was conducted of babies born to mothers who use cocaine during pregnancy, and the following sample data were obtained for weight at birth: n= 190, X= 2700g, s=645g. Use an a=0.05 significance level to test the claim that the standard deviation of birth weight of infants born to mothers who use cocaine is different from the standard deviation of 696g for birth weight of infants born to mothers who do not use cocaine during pregnancy.

Answer 1

a) Null Hypothesis

Alternative Hypothesis ( Claim)

b) Degrees of freedom = n-1 = 190-1=189

The critical values of Chi distribution for 189 df at 5% significance level are 152.882, 228.964

c) Under H0, the test statistic is

The P-Value is 0.9205

d) Since p value is greater than significance level, Fail to Reject H0.

e) Hence, we have enough evidence to support to warrant the rejection of the claim that the standard deviation of birth weight of infants born to mothers who use cocaine is different from the standard deviation of 696g for birth weight of infants born to mothers who do not use cocaine during pregnancy