Chapter 4&5

A sample of n=10 scores has a mean of M=100 and a standard deviation of s=4. What is the sample variance?

• 2

• 8

• 16

• 10

A set of 11 scores has SS=110. If the scores are a sample, the sample variance is _____ and if the scores are a population, the population variance is ______.

• 11, 10

• 11, 11

• 10, 10

• 10, 11

Which of the following set of scores has the least amount of variability?

• 68, 75, 74, 83, 97

• 1254, 1259, 1261, 1263

• 81, 82, 82, 83, 94

• 5, 13, 17, 20, 31

One sample is selected to represent scores in treatment 1 and a second sample is used to represent scores in treatment 2. Which set of sample statistics would present the clearest picture of a real difference between the two treatments?

• M1=46, M2=50, and both variances equal 36

• M1=46, M2=50, and both variances equal 16

• M1=48, M2=50, and both variances equal 36

• M1=48, M2=50, and both variances equal 16

If you have a score of X=64 on an exam with M=70, you should expect a better grade if s=10 than if s=5.

• True

• False

A sample of n=10 scores has SS=90. For this sample, the variance is 9.

• True

• False

A population of scores has a  $\mu$  of 50 and  $\sigma$  of 5. If every score in the population is multiplied by 3, then what are the new values for the mean and the standard deviation.

• Mean is 150, and standard deviation is 5.
  

• Mean is 150, and standard deviation is 15.
  

• Mean is 50, and standard deviation is 15.
  

• They both stay the same.
  

A population has a sum of squares of 100 and a variance of 4. What is the value of  $\Sigma(x-\mu)$  for the population?

• 25

• 10

• 0

• Cannot be determined
  

A population has a sum of squares of 100 and a variance of 4. How many scores are in the population?

• 25

• 16

• 50

• Cannot be determined

For a population of scores, the sum of the deviation scores is always equal to 0.

• True

• False