Author Question: The head circumference is measured for a sample of 15 girls and a separate sample of 15 boys. What ... (Read 78 times)

kfurse · **on:** Jul 24, 2018

The head circumference is measured for a sample of 15 girls and a separate sample of 15 boys. What is the correct combination of degrees of freedom and the value of the multiplier t for a 90 confidence interval for the difference in mean head circumference between girls and boys?
a. df = 13, t = 1.77
b. df = 28, t = 1.70
c. df = 28, t = 2.05
d. df = 30, t = 1.70

Question 2

For each study, decide if the two samples are independent samples or paired samples. A group of 100 students were randomly assigned to receive vitamin C (50 students) or a placebo (50 students). The groups were followed for 2 weeks and the proportions of students with colds were compared.
a. Independent samples
b. Paired samples