Question 1-

Consider the distribution of hemoglobin levels for the population of children under 6 who have been exposed to high levels of lead. Suppose that this distribution has = 0.85g/100ml. Because children who have lead poisoning tend to have much lower levels of hemoglobin than children who do not, we are interested in an upper confidence limit for (the mean of the hemoglobin levels in this population). Suppose that we have a random sample of 74 children from this population. The sample mean x = 10.6g/100ml.

Calculate a 90% upper confidence limit.

Question 2-

In the population, the average IQ is 100 with a standard deviation of 15. A team of scientists wants to test a new medication to see if it has an effect on intelligence (as measured by IQ). A sample of 40 participants who have taken the medication has a mean of 140. Did the medication affect intelligence? Conduct the hypothesis testing. Use =0.05.

a) Formulate two hypotheses.

b) Apply the appropriate test (show/explain 5-step procedure

c) Formulate decision rule

d) Calculate appropriate test statistics value.

e) Make a final conclusion.

Question 3-

6 subjects were given a drug (treatment group) and an additional 6 subjects a placebo (control group). Their reaction time to a stimulus was measured (in ms). We want to perform a _____________ for comparing the means of the treatment and control groups.

Determine the appropriate hypothesis test.

Question 4-

The group of researchers gathered data on the pregnant group's performance appraisal ratings during pregnancy and after returning from pregnancy leave. Here is a summary of the data gathered:

During pregnancy: x1 = 2.38 , s1 = 1.10 , n1 = 71

After pregnancy: x2 =2.65,s2 =1.64,n2 =71

Difference "During - After": xd = 0.27 , sd = 2.00 , nd = 71a.

The researchers were interested in answering the following question: Did the mean performance ratings for the pregnancy group differ significantly between the During Pregnancy and After Pregnancy time periods?

Which test is more appropriate to answer this question?