PSY 555 Homework #6


Chapter 4: # 1, 2, 3, 4, 5 (draw and shade the distributions when applicable).


1.  Two samples are randomly selected from a population.  One sample has n=10 scores and the other sample has n=40 scores?  Which sample should have a mean that more closely approximates m?  Explain your answer.


2.  The distribution of SAT scores is normal with a m=600 and s=100.  If you selected a random sample of n=65 scores, how much error would you expect between the sample mean and the population mean?


3.  What would the point estimate boundary scores be for a normal distribution with m=250 and s=20 when:


a.  The confidence interval is set at 95%.

b.  The confidence interval is set at 80%.


4.  A distribution is normal with m=80.  For the point estimate of the mean, the upper bound at the 99% confidence interval is 97.  What is the standard deviation and lower bound for this distribution?


5.  You have been asked to analyze the following data (Part A) for your advisor.  Please provide your advisor with all of the exploratory analyses (means, plots, etc.).  In addition, your advisor has found 3 data points and is not sure if they belong to the population of Part A.  Please show the probability that each of these data points are in fact part of the population given in Part A.


Part A: 9,10,12,17,14,17,10,20,15,19,12,17,9,13,16,17,18,20,12,17


Part B: 19,3,28