9) A psychologist is interested in the conditions that affect the number of dreams per month that people report in which they are alone. In the general population the number of such dreams per month follows a normal curve, with = 5 and = 4. The psychologist studies 36 individuals and found that their mean number of alone dreams is 8. What is the Z score for this groups mean in the distribution of sample means?

10) A psychologist is interested in the score of college students on the GRE. In the general population the number of correct response follows a normal curve, with = 15 and = 4. The psychologist studies 4 individuals and found that their mean number of correct response at for CCNY is 18. What is the Z score for this groups mean in the distribution of sample means?

11) A industrial psychologist is interested in the number of accidents that happen at the Honda factory. In the general population the number of correct accident follows a normal curve, with = 5 and =2. The psychologist studies 30 factors and found that their mean number of accidents were 4.5. What is the Z score for this groups mean in the distribution of sample means?