- ZOOM + PSYC 2317: Statistical Methods for Psychology Tarleton State University Exam 1 Instructions: please complete each problem below. You may submit your completed exam in Canvas using one of two file formats: either (1) write your solutions on paper and scan to a PDF, or (2) write your solutions in a Word/OpenOffice document. On either method, please show (or describe) as much work as possible. Report your final answers rounded to 2 decimal places (with the exception of p-values). 1. A sample of N = 12 scores has a mean of X = 10. One score of X = 15 is removed from the sample. What is the new value for the sample mean? File Preview 2. An expert reviews a sample of 8 scientific articles and records the following numbers of errors in each article: 7, 5, 11, 5, 6, 4, 8, 10. Compute the mean and median for this data. 3. A social psychologist records the age (in years) that a sample of seven participants first experienced peer pressure. The recorded ages are 18, 22, 14, 16, 10, 14, 18. Compute the variance and standard deviation for this data. 4. For a set of scores with mean 76 and standard deviation 8, find the Z-score that corresponds to each of the following X values: 96, 80, 70, 52. 5. For a set of scores with u = 45 and o = 12, find the X-value that corresponds to each of the following Z-scores: 1.50, -0.50, 2.00, -1/3 6. A set of exams are reported as X values and Z-scores. On this exam a score of X = 84 corresponds to a Z = 0.5 and X = 66 corresponds to a Z = -1.0. Use this information to find the mean and standard deviation for the complete set of exams. 7. A set of exam scores has a mean of 55 and a standard deviation of 6. The instructor would like to transform the scores into a standardized distribution with a new mean of 100 and new standard deviation of 10. Find the transformed value for each of the following scores from the original population: 55, 67, 46, 34. 8. A normal distribution has a mean of u = 110 with o = 12. What proportion of scores in this distribution are: (a) above 115? (b) below 118? (c) between 91 and 115? 9. The average employee in the US spends u = 30 minutes commuting to work each day. Assume that the distribution of commute times is normal with a standard deviation of o = 16 minutes. (a) What proportion of employees spend less than 12 minutes a day commuting? (b) What proportion of employees spend more than 45 minutes commuting each day? 10. For a normal population with u = 60 and o = 12, what is the probability of obtaining a sample mean: (a) greater than 62 for a sample of n = 36 scores? (b) greater than 62 for a sample of n = 9 scores