Final_Sp07 - Version A

# Final_Sp07 - Version A - Economics 120A Spring 2007 Prof....

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Economics 120A Spring 2007 Prof. Maria Cândido Final – Version A 2 PART I: Multiple-Choice Questions (1.5 points each, 24 points total) 1) As sample size increases, what happens to the population variance ( )? a. It increases. b. It decreases. c. It gets closer to the population mean. d. Nothing. 2) Consider this probability distribution of the number of courses taken by full-time undergraduate students: Number of Courses Probability 3 0.2 4 0.4 5 0.3 6 0.1 The mean of this distribution is _____ and the standard deviation is _______. a. 4.3 courses; 0.81 courses b. 4.3 courses; 0.90 courses c. 4.5 courses; 0.90 courses d. 4.5 courses; 0.81 courses 3) Consider the joint probability table: Age Number of Times Married Adults less than 60 years old Adults more than 60 years old Never (0) 0.17 0.04 Once (1) 0.41 0.21 Twice (2) 0.12 0.01 Three times (3) 0.04 0.00 Amongst adults less than 60 years old, what is the average number of times people have been married? a. 0.77 b. 0.88 c. 1.00 d. 1.04 4) A sample of 99 distances has a mean of 24 feet and a median of 24.5 feet. Unfortunately, it has just been discovered that an observation which was erroneously recorded as “30” actually had a value of “35”. If we make this correction to the data, then: a. the mean remains the same, but the median is increased b. the mean and median remain the same c. the median remains the same, but the mean is increased d. the mean and median are both increased 5) Let W and V be two estimators of the population parameter
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## Final_Sp07 - Version A - Economics 120A Spring 2007 Prof....

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