# c1 - Stat 115 Spring 2010 1 Your name Assignment 1...

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Stat 115 Spring 2010 1 Your name ______________________________ Assignment 1 Descriptive Statistics (due 2/10/10) (16 pts) Instructor Jill Nill has just finished teaching her first statistics class. As she breathes a sigh of relief, she notices the distribution of scores for her final exam and wrinkles her brow. This is what she sees… (the highest possible score is 20). Treat her class as a sample . Student Score (out of 20) 1 2 2 5 3 5 4 4 5 7 6 20 7 12 8 15 9 17 10 15 11 9 12 8 13 7 14 6 15 7 Computation by hand 1. Compute the mean, mode, and median (3) 2. Compute the sample standard deviation (3) 3. How many students scored at 7? (1) 4. How many students scored above 12? (1) 5. What percentage of people scored 5 or below 5? (1)

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Stat 115 Spring 2010 2 Computation by SPSS (SPSS deals with only samples). Enter the data listed above and use SPSS to calculate the following (see the instructions for SPSS below): 1. What is the mean? (1) 2. What is the standard deviation? Is the standard deviation SPSS computed the same as the one you computed by hand (except rounding error)? (1) 3. Fifty percent of students performed better than what score? (1) 4. What is the mode? (1) 5. Using SPSS, create a histogram based on these test scores. Impose the normal curve over your histogram. Locate the mean, mode, and median you computed in Question 1 in the histogram (by hand). Does the score distribution for Instructor Jill’s class approximate the normal distribution? If not, what is the shape of the distribution? (2) 6. Based on these analyses, what you think Instructor Jill should be thinking about her students’ performance? If you were Jill, what reasons(s) do you give to the performance of these students? (1) SPSS instructions 1. Please see Appendix D (p. 735-737) for data entry. 2. If you want to name your variable (instead of using var00001), click on the Variable View tab at the bottom of the data editor. Type in a new name (for example, score) in the name box. Click the Data View tab to go back to the data editor. Did the variable name change? 3. Click Analyze on the tool bar, select Descriptive Statistics , and click on Frequencies . 4. Move your variable in the left box into the Variable box (right box) by clicking the arrow mark in the middle. 5. Click Statistics , select Mean , Median , Mode , and Std. deviation , and click Continue . 6. Click Charts , select Histogram , and with normal curve , and click Continue . 7. Click Paste , highlight your syntax and click on the tool bar. Save the syntax.
3 Your name _________________________ Assignment 2 Normal Distribution and Probability (due 2/17/10) (15 pts) 1. A population consists of the following scores: 12 1 10 3 7 3 a. Draw a frequency distribution graph (Do not forget to label what each axis represents) (1). b. Compute

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## This note was uploaded on 09/08/2010 for the course STAT 115 at San Jose State.

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c1 - Stat 115 Spring 2010 1 Your name Assignment 1...

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